A prospective trial is reported which compares distal osteotomy of the first metatarsal with Keller's arthroplasty in the treatment of adult hallux valgus. A total of 33 patients attended for review at least three years after operation. Symptomatic improvement, as assessed by patient satisfaction, pain relief, cosmetic improvement and restoration of function, was similar in the two groups. Objective measurement showed that the range of movement of the metatarsophalangeal joint was better maintained after osteotomy, as was the relationship of the sesamoid bones to the head of the first metatarsal. Correction of the valgus deformity also was significantly better in the patients who underwent osteotomy and in these patients the first intermetatarsal angle was reduced to within normal limits. There was no evidence that initial degenerative changes or subluxation at the metatarsophalangeal joint compromised a successful result from osteotomy.