diff --git a/demo.py b/demo.py
index ca947072..7d7cb39d 100755
--- a/demo.py
+++ b/demo.py
@@ -4294,25 +4294,27 @@ def set_blood_pressure_data(api: Garmin) -> None:
         diastolic_input = input("Diastolic pressure [80]: ").strip()
         diastolic = int(diastolic_input) if diastolic_input else 80
 
-        # Get pulse
-        pulse_input = input("Pulse rate [60]: ").strip()
-        pulse = int(pulse_input) if pulse_input else 60
+        # Get pulse (optional - Garmin Connect's own UI allows omitting it)
+        pulse_input = input("Pulse rate (optional, press Enter to omit): ").strip()
+        pulse = int(pulse_input) if pulse_input else None
 
         # Get notes (optional)
         notes = input("Notes (optional): ").strip() or "Added via demo.py"
 
-        # Validate ranges
-        if not (50 <= systolic <= 300):
-            print("❌ Invalid systolic pressure (should be between 50-300)")
+        # Validate ranges (must match Garmin.set_blood_pressure's own checks,
+        # so a value the demo accepts never gets rejected by the API call)
+        if not (70 <= systolic <= 260):
+            print("❌ Invalid systolic pressure (should be between 70-260)")
             return
-        if not (30 <= diastolic <= 200):
-            print("❌ Invalid diastolic pressure (should be between 30-200)")
+        if not (40 <= diastolic <= 150):
+            print("❌ Invalid diastolic pressure (should be between 40-150)")
             return
-        if not (30 <= pulse <= 250):
-            print("❌ Invalid pulse rate (should be between 30-250)")
+        if pulse is not None and not (20 <= pulse <= 250):
+            print("❌ Invalid pulse rate (should be between 20-250)")
             return
 
-        print(f"📊 Recording: {systolic}/{diastolic} mmHg, pulse {pulse} bpm")
+        pulse_desc = f"pulse {pulse} bpm" if pulse is not None else "no pulse"
+        print(f"📊 Recording: {systolic}/{diastolic} mmHg, {pulse_desc}")
 
         call_and_display(
             api.set_blood_pressure,
diff --git a/garminconnect/__init__.py b/garminconnect/__init__.py
index 1d4c13bb..714d28be 100644
--- a/garminconnect/__init__.py
+++ b/garminconnect/__init__.py
@@ -1415,11 +1415,15 @@ def set_blood_pressure(
         self,
         systolic: int,
         diastolic: int,
-        pulse: int,
+        pulse: int | None = None,
         timestamp: str = "",
         notes: str = "",
     ) -> dict[str, Any]:
-        """Add blood pressure measurement."""
+        """Add blood pressure measurement.
+
+        pulse is optional - Garmin Connect's own UI accepts a blood
+        pressure entry without a heart rate value (#426).
+        """
         url = f"{self.garmin_connect_set_blood_pressure_endpoint}"
         dt = datetime.fromisoformat(timestamp) if timestamp else datetime.now()
         # Apply timezone offset to get UTC/GMT time
@@ -1429,15 +1433,17 @@ def set_blood_pressure(
             "measurementTimestampGMT": _fmt_ts(dtGMT),
             "systolic": systolic,
             "diastolic": diastolic,
-            "pulse": pulse,
             "sourceType": "MANUAL",
             "notes": notes,
         }
-        for name, val, lo, hi in (
+        checks = [
             ("systolic", systolic, 70, 260),
             ("diastolic", diastolic, 40, 150),
-            ("pulse", pulse, 20, 250),
-        ):
+        ]
+        if pulse is not None:
+            checks.append(("pulse", pulse, 20, 250))
+            payload["pulse"] = pulse
+        for name, val, lo, hi in checks:
             if not isinstance(val, int) or not (lo <= val <= hi):
                 raise ValueError(f"{name} must be an int in [{lo}, {hi}]")
         logger.debug("Adding blood pressure")
diff --git a/tests/test_garmin_unit.py b/tests/test_garmin_unit.py
index b2cea382..54ebd244 100644
--- a/tests/test_garmin_unit.py
+++ b/tests/test_garmin_unit.py
@@ -2550,6 +2550,36 @@ def test_returns_empty_dict_when_nothing_scheduled(
         assert garmin.get_next_scheduled_workout() == {}
 
 
+# ---------------------------------------------------------------------------
+# set_blood_pressure: pulse is optional, matching Garmin Connect's own UI (#426)
+# ---------------------------------------------------------------------------
+
+
+class TestSetBloodPressure:
+    def test_includes_pulse_when_given(self, garmin: garminconnect.Garmin):
+        with patch.object(garmin.client, "post") as mock_post:
+            mock_post.return_value.json.return_value = {"success": True}
+            garmin.set_blood_pressure(120, 80, pulse=65)
+
+        payload = mock_post.call_args.kwargs["json"]
+        assert payload["systolic"] == 120
+        assert payload["diastolic"] == 80
+        assert payload["pulse"] == 65
+
+    def test_omits_pulse_when_not_given(self, garmin: garminconnect.Garmin):
+        with patch.object(garmin.client, "post") as mock_post:
+            mock_post.return_value.json.return_value = {"success": True}
+            result = garmin.set_blood_pressure(120, 80)
+
+        assert result == {"success": True}
+        payload = mock_post.call_args.kwargs["json"]
+        assert "pulse" not in payload
+
+    def test_rejects_out_of_range_pulse(self, garmin: garminconnect.Garmin):
+        with pytest.raises(ValueError, match="pulse"):
+            garmin.set_blood_pressure(120, 80, pulse=300)
+
+
 # ---------------------------------------------------------------------------
 # create_gear: matches the payload captured from Garmin Connect's "Add Gear"
 # ---------------------------------------------------------------------------