We studied prospectively a consecutive series of 50 patients with chronic osteomyelitis. Patients were allocated to the following treatment groups: 1) wide resection, with a clearance margin of 5 mm or more; 2) marginal resection, with a clearance margin of less than 5 mm; and 3) intralesional biopsy, with debulking of the infected area. All patients had a course of antibiotics, intravenously for six weeks followed by orally for a further six weeks. No patients in group 1 had recurrence. In patients treated by marginal resection (group 2), 8 of 29 (28%) had recurrence. All patients who had debulking had a recurrence within one year of surgery. We performed a survival analysis to determine the time of the recurrence of infection. In group 2 there was a higher rate of recurrence in type-B hosts (p < 0.05); no type-A hosts had recurrence. This information is of use in planning surgery for chronic osteomyelitis.