Three patients with chronic osteomyelitis and wound infections due to Pseudomonas aeruginosa were recently seen at Boston City Hospital. Each of them had previously undergone internal fixation for femoral fracture which was complicated by postoperative wound infection requiring prolonged antibiotic therapy. Two of the patients were treated by removal of the internal fixation devices and given large total doses of gentamicin sulphate; six to eight months later the bone lesions had healed well, and the patients were convalescing satisfactorily. The third patient was given a short course of gentamicin and the internal fixation device was left in place; four months after discharge the condition of this patient was essentially unchanged. No evidence of gentamicin toxicity was observed in any of the patients. Gentamicin appears to warrant further trials in the treatment of osteomyelitis due to Pseudomonas aeruginosa that is resistant to other less toxic antibiotics.