diff --git a/src/genlab_bestilling/migrations/0012_sample_unique_genlab_id.py b/src/genlab_bestilling/migrations/0012_sample_unique_genlab_id.py
new file mode 100644
index 0000000..553a92e
--- /dev/null
+++ b/src/genlab_bestilling/migrations/0012_sample_unique_genlab_id.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.1.3 on 2024-12-04 10:10
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("genlab_bestilling", "0011_extractplateposition_notes_and_more"),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name="sample",
+            constraint=models.UniqueConstraint(
+                fields=("genlab_id",), name="unique_genlab_id"
+            ),
+        ),
+    ]
diff --git a/src/genlab_bestilling/models.py b/src/genlab_bestilling/models.py
index e7443a6..83e4abe 100644
--- a/src/genlab_bestilling/models.py
+++ b/src/genlab_bestilling/models.py
@@ -316,6 +316,11 @@ class Sample(models.Model):
     def __str__(self) -> str:
         return self.genlab_id or f"#SMP_{self.id}"
 
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(fields=["genlab_id"], name="unique_genlab_id")
+        ]
+
     @property
     def has_error(self):
         if not all(
@@ -370,7 +375,6 @@ class ExtractPlatePosition(models.Model):
     extracted_at = models.DateTimeField(auto_now=True)
     notes = models.CharField(null=True, blank=True)
 
-    # TODO: unique position per plate
     class Meta:
         constraints = [
             models.UniqueConstraint(