Eighteen cases (17 patients) of chronic diaphyseal osteomyelitis with repeated exacerbations have been operated on by intramedullary reaming in addition to the conventional local surgery and antibiotic therapy. Nine patients with severe pain at rest were promptly relieved by the operation. The observation time was 28 months. In one case the fistula persists. The remaining patients have "healed." The average duration of the disease was 19 years.