diff --git a/nnvm/python/nnvm/frontend/onnx.py b/nnvm/python/nnvm/frontend/onnx.py
index c3c4768a97db..2a4821f627ef 100644
--- a/nnvm/python/nnvm/frontend/onnx.py
+++ b/nnvm/python/nnvm/frontend/onnx.py
@@ -824,6 +824,19 @@ 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 ebedc20375e5..1c178fc78175 100644
--- a/python/tvm/relay/frontend/onnx.py
+++ b/python/tvm/relay/frontend/onnx.py
@@ -951,6 +951,19 @@ 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