Cranial nerve involvement in multiple myeloma and solitary plasmacytoma is rare. We report on two patients who developed cranial nerve palsy due to skull base plasmacytoma. Patient 1, a 55-year old man with multiple myeloma, developed right sixth cranial nerve palsy during a phase of chemotherapy. He had an intracranial plasmacytoma in the clival region and was treated with 30 Gy whole brain radiotherapy. Patient 2, a 40-year old man, presented with right third cranial nerve palsy and was detected to have a solitary skull base plasmacytoma. He was treated with radiotherapy followed by thalidomide plus dexamethasone.