Coexistence of myasthenia gravis with an immunologically mediated neuropathy syndrome is rare. We present a young male patient with a history of generalized muscle weakness and fatigue with electrophysiological evidence of both a motor neuron syndrome and a neuromuscular junction abnormality accompanied by pathologic evidence of denervation with muscle biopsy. Laboratory evidence for both acetylcholine receptor (AchR) antibodies and anti-asialo GM1 antibodies, both of high levels, was found. The patient's fatigue and weakness showed an objective response to pyridostigmine, prednisone, and immunoglobulin therapy over a period of 9 months.