At the authors' institution from 1964 to 1984, ankle arthrodesis was performed in 13 patients with insulin-dependent diabetes mellitus who had a history of ankle sprain or fracture. Nine patients were diagnosed by clinical exam as having a peripheral neuropathy; nine patients had roentgenographic evidence of neuropathic arthropathy prior to surgery. Follow-up study with examination and roentgenograms averaged 42 months. Clinical and roentgenographic union was achieved in seven ankles at an average of 16 weeks. Two patients developed a nonunion, three had an amputation, and one died at two months postoperatively. Thirteen complications occurred in eight of the 13 patients (62%). Twenty reoperations, excluding pin removal, were performed in eight patients (62%). A satisfactory result was achieved in only 50% overall and in only 38% of patients with roentgenographic changes of neuropathic arthropathy. Neuropathic arthropathy contributes to the inordinate complication and failure rates. Ankle arthrodesis should be considered with caution in the diabetic patient.