We have reviewed 60 patients with primary bone infections; 21 of these (35%) had subacute osteomyelitis, a figure which supports other recent observations that this variant of bone infection is becoming more widespread. In this group open culture and biopsy were necessary in order to exclude bony malignancy, and a raised erythrocyte sedimentation rate proved a useful diagnostic aid. All the patients with acute osteomyelitis or with vertebral infection responded to primary treatment, but five of those with subacute osteomyelitis had recurrences.