diff --git a/neutronclient/common/exceptions.py b/neutronclient/common/exceptions.py
index 4298d423a..1040ee120 100644
--- a/neutronclient/common/exceptions.py
+++ b/neutronclient/common/exceptions.py
@@ -162,6 +162,10 @@ class IpAddressInUseClient(Conflict):
     pass
 
 
+class IpAddressAlreadyAllocatedClient(Conflict):
+    pass
+
+
 class InvalidIpForNetworkClient(BadRequest):
     pass
 
diff --git a/neutronclient/tests/unit/test_cli20.py b/neutronclient/tests/unit/test_cli20.py
index 132e1e547..0837a6c3d 100644
--- a/neutronclient/tests/unit/test_cli20.py
+++ b/neutronclient/tests/unit/test_cli20.py
@@ -911,6 +911,8 @@ class CLITestV20ExceptionHandler(CLITestV20Base):
             ('OverQuota', exceptions.OverQuotaClient, 409),
             ('InvalidIpForNetwork', exceptions.InvalidIpForNetworkClient, 400),
             ('InvalidIpForSubnet', exceptions.InvalidIpForSubnetClient, 400),
+            ('IpAddressAlreadyAllocated',
+             exceptions.IpAddressAlreadyAllocatedClient, 400),
         ]
 
         error_msg = 'dummy exception message'
diff --git a/releasenotes/notes/Define-IpAddressAlreadyAllocatedClient-exception-e8600ca5ba1c7f45.yaml b/releasenotes/notes/Define-IpAddressAlreadyAllocatedClient-exception-e8600ca5ba1c7f45.yaml
new file mode 100644
index 000000000..4182585e0
--- /dev/null
+++ b/releasenotes/notes/Define-IpAddressAlreadyAllocatedClient-exception-e8600ca5ba1c7f45.yaml
@@ -0,0 +1,6 @@
+---
+other:
+  - |
+    Define a new exception type ``IpAddressAlreadyAllocatedClient``.
+    Users can catch this specific exception instead of the generic
+    ``NeutronClientException``.