Proximal muscle weakness with atrophy occurred 31/2 years after a jejunocolostomy for morbid obesity. Recovery followed tear down of the jejunocolostomy and reanastomosis. Clear cut low voltage fibrillation potentials were seen in some muscle groups tested. In nearly all muscles examined there was increased insertion activity. Nerve conduction velocities were normal. Degeneration and swelling of axons and partial demyelination were seen histologically in nerve biopsy material. Malabsorption was well demonstrated with D-xylose absorption test, serum carotene level, and stool fat content. Serum B12 and folate were within normal limits. One month following reanastomosis, examination demonstrated almost complete clinical improvement. The patient was restudied by electromyography, and the findings were consistent with a resolving peripheral neuropathy. Serum carotene level returned to normal value. This metabolic study examines the infrequent association of neuromyopathy, malabsorption, and steatorrhea.