diff --git a/nnvm/python/nnvm/frontend/onnx.py b/nnvm/python/nnvm/frontend/onnx.py
index eb78b7845c23..2434fb01c1d5 100644
--- a/nnvm/python/nnvm/frontend/onnx.py
+++ b/nnvm/python/nnvm/frontend/onnx.py
@@ -830,6 +830,19 @@ def from_onnx(self, graph, opset):
             else:
                 self._num_input += 1
                 self._nodes[i_name] = _sym.Variable(name=i_name)
+        # get list of unsupported ops
+        convert_map = _get_convert_map(opset)
+        unsupported_ops = set()
+        for node in graph.node:
+            op_name = node.op_type
+            if op_name not in convert_map and \
+               op_name != 'Constant' and \
+               op_name not in _identity_list:
+                unsupported_ops.add(op_name)
+        if unsupported_ops:
+            msg = 'The following operators are not supported for frontend ONNX: '
+            msg += ', '.join(unsupported_ops)
+            raise tvm.error.OpNotImplemented(msg)
         # construct nodes, nodes are stored as directed acyclic graph
         for node in graph.node:
             op_name = node.op_type
diff --git a/python/tvm/relay/frontend/onnx.py b/python/tvm/relay/frontend/onnx.py
index 08a64c37d8df..470f4197c908 100644
--- a/python/tvm/relay/frontend/onnx.py
+++ b/python/tvm/relay/frontend/onnx.py
@@ -989,6 +989,19 @@ def from_onnx(self, graph, opset):
                 else:
                     dtype = d_type
                 self._nodes[i_name] = new_var(i_name, shape=tshape, dtype=dtype)
+        # get list of unsupported ops
+        convert_map = _get_convert_map(opset)
+        unsupported_ops = set()
+        for node in graph.node:
+            op_name = node.op_type
+            if op_name not in convert_map and \
+               op_name != 'Constant' and \
+               op_name not in _identity_list:
+                unsupported_ops.add(op_name)
+        if unsupported_ops:
+            msg = 'The following operators are not supported for frontend ONNX: '
+            msg += ', '.join(unsupported_ops)
+            raise tvm.error.OpNotImplemented(msg)
         # construct nodes, nodes are stored as directed acyclic graph
         for node in graph.node:
             op_name = node.op_type