diff --git a/IMPLEMENTATION_PLAN.md b/IMPLEMENTATION_PLAN.md
index 9a3b1d6..207c964 100644
--- a/IMPLEMENTATION_PLAN.md
+++ b/IMPLEMENTATION_PLAN.md
@@ -228,10 +228,10 @@ Drawer selection → update_drug_selection → app-state store → load_pathway_
 ## Phase 5: Polish & Cleanup
 
 ### 5.1 Trust selection
-- [ ] Add trust selection either:
+- [x] Add trust selection either:
   - In the dmc.Drawer as a "Trusts" section (preferred — keeps all filters in one place), OR
   - As sidebar checkboxes
-- [ ] Wire trust selection to `selected_trusts` in `app-state` → pathway data reload
+- [x] Wire trust selection to `selected_trusts` in `app-state` → pathway data reload
 - **Checkpoint**: Selecting trusts filters the chart correctly
 
 ### 5.2 Loading/error/empty states + dynamic hierarchy label
diff --git a/dash_app/app.py b/dash_app/app.py
index cb35ab6..107a24e 100644
--- a/dash_app/app.py
+++ b/dash_app/app.py
@@ -25,6 +25,7 @@ app.layout = dmc.MantineProvider(
             "date_filter_id": "all_6mo",
             "selected_drugs": [],
             "selected_directorates": [],
+            "selected_trusts": [],
         }),
         dcc.Store(id="chart-data", storage_type="memory"),
         dcc.Store(id="reference-data", storage_type="session"),
diff --git a/dash_app/callbacks/chart.py b/dash_app/callbacks/chart.py
index 6cc9dc7..9b013f4 100644
--- a/dash_app/callbacks/chart.py
+++ b/dash_app/callbacks/chart.py
@@ -32,6 +32,13 @@ def _generate_chart_title(app_state):
         else:
             parts.append(f"{len(selected_directorates)} directorates")
 
+    selected_trusts = app_state.get("selected_trusts") or []
+    if selected_trusts:
+        if len(selected_trusts) <= 2:
+            parts.append(", ".join(selected_trusts))
+        else:
+            parts.append(f"{len(selected_trusts)} trusts")
+
     return " | ".join(parts) if parts else "All Patients"
 
 
@@ -53,12 +60,14 @@ def register_chart_callbacks(app):
         chart_type = app_state.get("chart_type", "directory")
         selected_drugs = app_state.get("selected_drugs") or None
         selected_directorates = app_state.get("selected_directorates") or None
+        selected_trusts = app_state.get("selected_trusts") or None
 
         return query_pathway_data(
             filter_id=filter_id,
             chart_type=chart_type,
             selected_drugs=selected_drugs,
             selected_directorates=selected_directorates,
+            selected_trusts=selected_trusts,
         )
 
     @app.callback(
diff --git a/dash_app/callbacks/drawer.py b/dash_app/callbacks/drawer.py
index 39eb959..3ff53fa 100644
--- a/dash_app/callbacks/drawer.py
+++ b/dash_app/callbacks/drawer.py
@@ -9,14 +9,16 @@ def register_drawer_callbacks(app):
         Output("drug-drawer", "opened"),
         Input("sidebar-drug-selection", "n_clicks"),
         Input("sidebar-indications", "n_clicks"),
+        Input("sidebar-trust-selection", "n_clicks"),
         prevent_initial_call=True,
     )
-    def open_drawer(_drug_clicks, _indication_clicks):
-        """Open the drawer when sidebar Drug Selection or Indications is clicked."""
+    def open_drawer(_drug_clicks, _indication_clicks, _trust_clicks):
+        """Open the drawer when sidebar Drug Selection, Indications, or Trust Selection is clicked."""
         return True
 
     @app.callback(
         Output("all-drugs-chips", "value"),
+        Output("trust-chips", "value"),
         Input({"type": "drug-fragment", "index": ALL}, "n_clicks"),
         Input("clear-drug-filters", "n_clicks"),
         State("all-drugs-chips", "value"),
@@ -27,20 +29,20 @@ def register_drawer_callbacks(app):
         """Handle drug fragment badge click (substring match) or clear all filters.
 
         Fragment click: find all full drug names containing the fragment substring,
-        toggle them in the chip selection.
-        Clear click: reset chip selection to empty.
+        toggle them in the chip selection. Trust chips unchanged.
+        Clear click: reset both drug and trust chip selections.
         """
         triggered = ctx.triggered_id
 
-        # Clear button
+        # Clear button — reset both drug and trust chips
         if triggered == "clear-drug-filters":
-            return []
+            return [], []
 
         # Fragment badge click — triggered_id is a dict like {"type": "drug-fragment", "index": "DIR|FRAG"}
         if isinstance(triggered, dict) and triggered.get("type") == "drug-fragment":
             # Check if any fragment was actually clicked (not just initial render)
             if not any(n for n in (fragment_clicks or []) if n):
-                return no_update
+                return no_update, no_update
 
             fragment_key = triggered["index"]  # e.g. "CARDIOLOGY|ABCIXIMAB"
             fragment = fragment_key.split("|", 1)[-1] if "|" in fragment_key else fragment_key
@@ -55,7 +57,7 @@ def register_drawer_callbacks(app):
             ]
 
             if not matching_drugs:
-                return no_update
+                return no_update, no_update
 
             # Toggle: if all matching drugs are already selected, deselect them;
             # otherwise, add them to selection
@@ -67,6 +69,6 @@ def register_drawer_callbacks(app):
             else:
                 updated = current | set(matching_drugs)
 
-            return sorted(updated)
+            return sorted(updated), no_update
 
-        return no_update
+        return no_update, no_update
diff --git a/dash_app/callbacks/filters.py b/dash_app/callbacks/filters.py
index ff523dc..b99096a 100644
--- a/dash_app/callbacks/filters.py
+++ b/dash_app/callbacks/filters.py
@@ -32,12 +32,14 @@ def register_filter_callbacks(app):
         Input("filter-initiated", "value"),
         Input("filter-last-seen", "value"),
         Input("all-drugs-chips", "value"),
+        Input("trust-chips", "value"),
         State("app-state", "data"),
     )
     def update_app_state(
-        _dir_clicks, _ind_clicks, initiated, last_seen, selected_drugs, current_state
+        _dir_clicks, _ind_clicks, initiated, last_seen, selected_drugs,
+        selected_trusts, current_state
     ):
-        """Update app-state when chart type toggle, date filters, or drug chips change."""
+        """Update app-state when chart type toggle, date filters, drug chips, or trust chips change."""
         if not current_state:
             current_state = {
                 "chart_type": "directory",
@@ -46,6 +48,7 @@ def register_filter_callbacks(app):
                 "date_filter_id": "all_6mo",
                 "selected_drugs": [],
                 "selected_directorates": [],
+                "selected_trusts": [],
             }
 
         triggered_id = ctx.triggered_id
@@ -68,6 +71,7 @@ def register_filter_callbacks(app):
             "last_seen": last_seen,
             "date_filter_id": date_filter_id,
             "selected_drugs": selected_drugs or [],
+            "selected_trusts": selected_trusts or [],
         }
 
         # Toggle pill CSS classes
diff --git a/dash_app/components/drawer.py b/dash_app/components/drawer.py
index 8d9dffc..da5242a 100644
--- a/dash_app/components/drawer.py
+++ b/dash_app/components/drawer.py
@@ -1,8 +1,9 @@
 """
-Drug browser drawer component using Dash Mantine Components.
+Filter drawer component using Dash Mantine Components.
 
 Provides a right-side drawer with:
 - "All Drugs" section: flat alphabetical list of all drugs from pathway_nodes
+- "Trusts" section: all NHS trusts from pathway_nodes for trust filtering
 - Directorate cards: grouped by PrimaryDirectorate from DimSearchTerm.csv,
   with Accordion items per Search_Term containing drug fragment chips
 - "Clear Filters" button at the bottom
@@ -11,7 +12,7 @@ Provides a right-side drawer with:
 from dash import html
 import dash_mantine_components as dmc
 
-from dash_app.data.card_browser import build_directorate_tree, get_all_drugs
+from dash_app.data.card_browser import build_directorate_tree, get_all_drugs, get_all_trusts
 
 
 def _make_drug_chips(drugs: list[str]) -> dmc.ChipGroup:
@@ -27,6 +28,19 @@ def _make_drug_chips(drugs: list[str]) -> dmc.ChipGroup:
     )
 
 
+def _make_trust_chips(trusts: list[str]) -> dmc.ChipGroup:
+    """Create a ChipGroup with multiple selection for the 'Trusts' section."""
+    return dmc.ChipGroup(
+        id="trust-chips",
+        multiple=True,
+        value=[],
+        children=[
+            dmc.Chip(trust, value=trust, size="xs")
+            for trust in trusts
+        ],
+    )
+
+
 def _make_directorate_card(directorate: str, indications: dict[str, list[str]]) -> dmc.AccordionItem:
     """
     Create an AccordionItem for a single directorate.
@@ -97,6 +111,7 @@ def make_drawer():
     Returns a dmc.Drawer that will be opened/closed via callbacks in Phase 4.2.
     """
     drugs = get_all_drugs()
+    trusts = get_all_trusts()
     directorate_tree = build_directorate_tree()
 
     # All Drugs section
@@ -116,6 +131,23 @@ def make_drawer():
         ],
     )
 
+    # Trusts section
+    trusts_section = html.Div(
+        className="drawer-section",
+        children=[
+            dmc.Text("Trusts", fw=700, size="sm", className="drawer-section-title"),
+            dmc.Text(
+                f"{len(trusts)} NHS trusts",
+                size="xs",
+                c="dimmed",
+            ),
+            html.Div(
+                className="drawer-chips-wrap",
+                children=_make_trust_chips(trusts),
+            ),
+        ],
+    )
+
     # Directorate cards section
     directorate_items = [
         _make_directorate_card(directorate, indications)
@@ -163,6 +195,8 @@ def make_drawer():
                     children=[
                         all_drugs_section,
                         dmc.Divider(),
+                        trusts_section,
+                        dmc.Divider(),
                         directorate_section,
                         clear_button,
                     ],
diff --git a/dash_app/components/sidebar.py b/dash_app/components/sidebar.py
index 1d4eed3..42326ca 100644
--- a/dash_app/components/sidebar.py
+++ b/dash_app/components/sidebar.py
@@ -47,7 +47,9 @@ def make_sidebar():
                     _sidebar_item(
                         "Drug Selection", "drug", item_id="sidebar-drug-selection"
                     ),
-                    _sidebar_item("Trust Selection", "trust"),
+                    _sidebar_item(
+                        "Trust Selection", "trust", item_id="sidebar-trust-selection"
+                    ),
                     _sidebar_item("Directory Selection", "directory"),
                     _sidebar_item(
                         "Indications", "indication", item_id="sidebar-indications"
diff --git a/dash_app/data/card_browser.py b/dash_app/data/card_browser.py
index 4f23800..685a37c 100644
--- a/dash_app/data/card_browser.py
+++ b/dash_app/data/card_browser.py
@@ -81,3 +81,15 @@ def get_all_drugs() -> list[str]:
 
     data = load_initial_data()
     return data.get("available_drugs", [])
+
+
+def get_all_trusts() -> list[str]:
+    """
+    Return a sorted flat list of all unique trust names from pathway_nodes level 1.
+
+    Delegates to load_initial_data() which already queries the database.
+    """
+    from dash_app.data.queries import load_initial_data
+
+    data = load_initial_data()
+    return data.get("available_trusts", [])
diff --git a/dash_app/data/queries.py b/dash_app/data/queries.py
index 358f884..47e4e42 100644
--- a/dash_app/data/queries.py
+++ b/dash_app/data/queries.py
@@ -26,6 +26,7 @@ def load_pathway_data(
     chart_type: str = "directory",
     selected_drugs: Optional[list[str]] = None,
     selected_directorates: Optional[list[str]] = None,
+    selected_trusts: Optional[list[str]] = None,
 ) -> dict:
     """Load pre-computed pathway nodes with optional filters."""
     return _load_pathway_nodes(
@@ -34,4 +35,5 @@ def load_pathway_data(
         chart_type=chart_type,
         selected_drugs=selected_drugs,
         selected_directorates=selected_directorates,
+        selected_trusts=selected_trusts,
     )
diff --git a/src/data_processing/pathway_queries.py b/src/data_processing/pathway_queries.py
index bf1941d..f8eb9ee 100644
--- a/src/data_processing/pathway_queries.py
+++ b/src/data_processing/pathway_queries.py
@@ -31,6 +31,7 @@ def load_initial_data(db_path: Path) -> dict:
             "available_drugs": [],
             "available_directorates": [],
             "available_indications": [],
+            "available_trusts": [],
             "total_records": 0,
             "last_updated": "",
             "error": "Database not found",
@@ -82,10 +83,20 @@ def load_initial_data(db_path: Path) -> dict:
         if not available_indications:
             available_indications = ["(No indications available)"]
 
+        # Unique trusts from pathway_nodes level 1
+        cursor.execute("""
+            SELECT DISTINCT trust_name
+            FROM pathway_nodes
+            WHERE level = 1 AND trust_name IS NOT NULL AND trust_name != ''
+            ORDER BY trust_name
+        """)
+        available_trusts = [row[0] for row in cursor.fetchall()]
+
         return {
             "available_drugs": available_drugs,
             "available_directorates": available_directorates,
             "available_indications": available_indications,
+            "available_trusts": available_trusts,
             "total_records": total_records,
             "last_updated": last_updated,
         }
@@ -94,6 +105,7 @@ def load_initial_data(db_path: Path) -> dict:
             "available_drugs": [],
             "available_directorates": [],
             "available_indications": [],
+            "available_trusts": [],
             "total_records": 0,
             "last_updated": "",
             "error": f"Database error: {e}",
@@ -108,6 +120,7 @@ def load_pathway_nodes(
     chart_type: str,
     selected_drugs: Optional[list[str]] = None,
     selected_directorates: Optional[list[str]] = None,
+    selected_trusts: Optional[list[str]] = None,
 ) -> dict:
     """
     Load pre-computed pathway nodes from SQLite.
@@ -120,6 +133,7 @@ def load_pathway_nodes(
         chart_type: "directory" or "indication"
         selected_drugs: optional list of drug names to filter by
         selected_directorates: optional list of directorate names to filter by
+        selected_trusts: optional list of trust names to filter by
 
     Returns dict with keys:
         nodes: list of dicts (JSON-serializable) with chart node data
@@ -157,6 +171,13 @@ def load_pathway_nodes(
                 f"({' OR '.join(drug_conditions)} OR drug_sequence IS NULL)"
             )
 
+        if selected_trusts:
+            placeholders = ",".join("?" * len(selected_trusts))
+            where_clauses.append(
+                f"(trust_name IN ({placeholders}) OR trust_name IS NULL OR trust_name = '')"
+            )
+            params.extend(selected_trusts)
+
         where_clause = " AND ".join(where_clauses)
 
         query = f"""