diff --git a/manage_breast_screening/mammograms/forms/breast_cancer_history_form.py b/manage_breast_screening/mammograms/forms/breast_cancer_history_form.py
index bb2ee0ea1..ef8cf8d0a 100644
--- a/manage_breast_screening/mammograms/forms/breast_cancer_history_form.py
+++ b/manage_breast_screening/mammograms/forms/breast_cancer_history_form.py
@@ -7,7 +7,9 @@
     ChoiceField,
     MultipleChoiceField,
 )
-from manage_breast_screening.nhsuk_forms.fields.integer_field import IntegerField
+from manage_breast_screening.nhsuk_forms.fields.integer_field import (
+    YearField,
+)
 from manage_breast_screening.nhsuk_forms.forms import FormWithConditionalFields
 from manage_breast_screening.participants.models.breast_cancer_history_item import (
     BreastCancerHistoryItem,
@@ -26,13 +28,12 @@ class DiagnosisLocationChoices(TextChoices):
         error_messages={"required": "Select which breasts cancer was diagnosed in"},
         exclusive_choices={DiagnosisLocationChoices.DONT_KNOW},
     )
-    # todo: constrain min/max
-    diagnosis_year = IntegerField(
+    diagnosis_year = YearField(
+        hint="Leave blank if unknown",
+        required=False,
         label="Year of diagnosis (optional)",
         label_classes="nhsuk-label--m",
         classes="nhsuk-input--width-4",
-        hint="Leave blank if unknown",
-        required=False,
     )
 
     right_breast_procedure = ChoiceField(
diff --git a/manage_breast_screening/mammograms/tests/forms/test_breast_cancer_history_form.py b/manage_breast_screening/mammograms/tests/forms/test_breast_cancer_history_form.py
index d6e467fde..b19389d06 100644
--- a/manage_breast_screening/mammograms/tests/forms/test_breast_cancer_history_form.py
+++ b/manage_breast_screening/mammograms/tests/forms/test_breast_cancer_history_form.py
@@ -1,3 +1,4 @@
+from datetime import date
 from urllib.parse import urlencode
 
 import pytest
@@ -51,12 +52,15 @@ def test_no_data_not_valid(self):
             "systemic_treatments": ["Select what systemic treatments they have had"],
         }
 
-    def test_valid_form(self):
+    def test_valid_form(self, time_machine):
+        time_machine.move_to(date(2025, 1, 1))
+
         form = BreastCancerHistoryForm(
             data=QueryDict(
                 urlencode(
                     {
                         "diagnosis_location": "RIGHT_BREAST",
+                        "diagnosis_year": "2013",
                         "intervention_location": "NHS_HOSPITAL",
                         "intervention_location_details_nhs_hospital": "abc",
                         "left_breast_other_surgery": "NO_SURGERY",
@@ -73,6 +77,32 @@ def test_valid_form(self):
 
         assert form.is_valid(), form.errors
 
+    def test_invalid_date(self, time_machine):
+        time_machine.move_to(date(2025, 1, 1))
+
+        form = BreastCancerHistoryForm(
+            data=QueryDict(
+                urlencode(
+                    {
+                        "diagnosis_location": "RIGHT_BREAST",
+                        "diagnosis_year": "1900",
+                        "intervention_location": "NHS_HOSPITAL",
+                        "intervention_location_details_nhs_hospital": "abc",
+                        "left_breast_other_surgery": "NO_SURGERY",
+                        "left_breast_procedure": "NO_PROCEDURE",
+                        "left_breast_treatment": "NO_RADIOTHERAPY",
+                        "right_breast_other_surgery": "LYMPH_NODE_SURGERY",
+                        "right_breast_procedure": "LUMPECTOMY",
+                        "right_breast_treatment": "BREAST_RADIOTHERAPY",
+                        "systemic_treatments": "NO_SYSTEMIC_TREATMENTS",
+                    }
+                )
+            )
+        )
+
+        assert not form.is_valid()
+        assert form.errors == {"diagnosis_year": ["Year must be 1945 or later"]}
+
     def test_missing_intervention_location_details(self):
         form = BreastCancerHistoryForm(
             data=QueryDict(