diff --git a/backend/src/models/fhir_immunization_pre_validators.py b/backend/src/models/fhir_immunization_pre_validators.py
index d40d977ac..f9511b098 100644
--- a/backend/src/models/fhir_immunization_pre_validators.py
+++ b/backend/src/models/fhir_immunization_pre_validators.py
@@ -310,15 +310,18 @@ def pre_validate_patient_name_given(self, values: dict) -> dict:
         except (KeyError, IndexError, AttributeError):
             pass
 
+    PERSON_SURNAME_MAX_LENGTH = 35
+
     def pre_validate_patient_name_family(self, values: dict) -> dict:
         """
         Pre-validate that, if a contained[?(@.resourceType=='Patient')].name[{index}].family (legacy CSV field name:
-        PERSON_SURNAME) exists, index dynamically determined then it is a an array containing a single non-empty string
+        PERSON_SURNAME) exists, index dynamically determined then it is a non-empty string of maximum length
+        35 characters
         """
         field_location = patient_name_family_field_location(values)
         try:
             field_value, _ = patient_and_practitioner_value_and_index(values, "family", "Patient")
-            PreValidation.for_string(field_value, field_location)
+            PreValidation.for_string(field_value, field_location, max_length=self.PERSON_SURNAME_MAX_LENGTH)
         except (KeyError, IndexError, AttributeError):
             pass
 
diff --git a/backend/src/models/utils/pre_validator_utils.py b/backend/src/models/utils/pre_validator_utils.py
index 793d86f92..9db92ea60 100644
--- a/backend/src/models/utils/pre_validator_utils.py
+++ b/backend/src/models/utils/pre_validator_utils.py
@@ -23,6 +23,9 @@ def for_string(
         if not isinstance(field_value, str):
             raise TypeError(f"{field_location} must be a string")
 
+        if field_value.isspace():
+            raise ValueError(f"{field_location} must be a non-empty string")
+
         if defined_length:
             if len(field_value) != defined_length:
                 raise ValueError(f"{field_location} must be {defined_length} characters")
diff --git a/backend/tests/test_immunization_pre_validator.py b/backend/tests/test_immunization_pre_validator.py
index 704bb6832..5225048ed 100644
--- a/backend/tests/test_immunization_pre_validator.py
+++ b/backend/tests/test_immunization_pre_validator.py
@@ -506,7 +506,9 @@ def test_pre_validate_patient_name_family(self):
         ValidatorModelTests.test_string_value(
             self,
             field_location=patient_name_family_field_location(valid_json_data),
-            valid_strings_to_test=["test"],
+            valid_strings_to_test=["test", "Quitelongsurname", "Surnamewithjustthirtyfivecharacters"],
+            max_length=PreValidators.PERSON_SURNAME_MAX_LENGTH,
+            invalid_length_strings_to_test=["Surnamethathasgotthirtysixcharacters"],
         )
 
     def test_pre_validate_patient_birth_date(self):
diff --git a/backend/tests/testing_utils/pre_validation_test_utils.py b/backend/tests/testing_utils/pre_validation_test_utils.py
index 2abd1c0ac..4276e1a90 100644
--- a/backend/tests/testing_utils/pre_validation_test_utils.py
+++ b/backend/tests/testing_utils/pre_validation_test_utils.py
@@ -76,6 +76,16 @@ def test_string_value(
                 expected_error_message=f"{field_location} must be a string",
             )
 
+        # Test whitespace
+        for invalid_whitespace_string in InvalidValues.for_whitespace_strings:
+            test_invalid_values_rejected(
+                test_instance,
+                valid_json_data,
+                field_location=field_location,
+                invalid_value=invalid_whitespace_string,
+                expected_error_message=f"{field_location} must be a non-empty string",
+            )
+
         # If there is a predefined string length, then test invalid string lengths,
         # otherwise check the empty string only
         if defined_length:
diff --git a/backend/tests/testing_utils/values_for_tests.py b/backend/tests/testing_utils/values_for_tests.py
index ed32e990c..9080419eb 100644
--- a/backend/tests/testing_utils/values_for_tests.py
+++ b/backend/tests/testing_utils/values_for_tests.py
@@ -319,6 +319,12 @@ class Invalid:
 class InvalidValues:
     """Store lists of invalid values for tests"""
 
+    for_whitespace_strings = [
+        " ",  # All spaces
+        " \n ",  # Spaces and newlines
+        "\r\n\t",  # CR, LF and tabs
+    ]
+
     for_postal_codes = [
         "SW1  1AA",  # Too many spaces in divider
         "SW 1 1A",  # Too many space dividers