diff --git a/initializers/asns.yml b/initializers/asns.yml
new file mode 100644
index 0000000..f75408b
--- /dev/null
+++ b/initializers/asns.yml
@@ -0,0 +1,7 @@
+# - asn: 1
+#   rir: RFC1918
+#   tenant: tenant1
+# - asn: 2
+#   rir: RFC4193 ULA
+# - asn: 3
+#   rir: RFC3849
diff --git a/initializers/sites.yml b/initializers/sites.yml
index 7ace3aa..700c853 100644
--- a/initializers/sites.yml
+++ b/initializers/sites.yml
@@ -3,7 +3,6 @@
 #   region: Downtown
 #   status: active
 #   facility: Amsterdam 1
-#   asn: 12345
 #   custom_field_data:
 #     text_field: Description for AMS1
 # - name: AMS 2
@@ -11,7 +10,6 @@
 #   region: Downtown
 #   status: active
 #   facility: Amsterdam 2
-#   asn: 54321
 #   custom_field_data:
 #     text_field: Description for AMS2
 # - name: AMS 3
@@ -19,7 +17,6 @@
 #   region: Suburbs
 #   status: active
 #   facility: Amsterdam 3
-#   asn: 67890
 #   tenant: tenant1
 #   custom_field_data:
 #     text_field: Description for AMS3
@@ -28,7 +25,6 @@
 #   region: Singapore
 #   status: active
 #   facility: Singapore 1
-#   asn: 09876
 #   tenant: tenant2
 #   custom_field_data:
 #     text_field: Description for SING1
diff --git a/startup_scripts/155_asns.py b/startup_scripts/155_asns.py
new file mode 100644
index 0000000..893f3ba
--- /dev/null
+++ b/startup_scripts/155_asns.py
@@ -0,0 +1,33 @@
+import sys
+
+from ipam.models import ASN, RIR
+from startup_script_utils import load_yaml
+from tenancy.models import Tenant
+
+asns = load_yaml("/opt/netbox/initializers/asns.yml")
+
+if asns is None:
+    sys.exit()
+
+required_assocs = {"rir": (RIR, "name")}
+
+optional_assocs = {"tenant": (Tenant, "name")}
+
+for params in asns:
+    for assoc, details in required_assocs.items():
+        model, field = details
+        query = {field: params.pop(assoc)}
+
+        params[assoc] = model.objects.get(**query)
+
+    for assoc, details in optional_assocs.items():
+        if assoc in params:
+            model, field = details
+            query = {field: params.pop(assoc)}
+
+            params[assoc] = model.objects.get(**query)
+
+    asn, created = ASN.objects.get_or_create(**params)
+
+    if created:
+        print(f"🔡 Created ASN {asn.asn}")