Because of its pharmacokinetic, broad spectrum and oral administration, ofloxacin can be used in the treatment of chronic bone infections. A clinical trial was performed in 10 patients with subacute or chronic osteitis (5 Staphylococcus aureus, 1 Staphylococcus epidermidis, 1 Klebsiella oxytoca, 1 Escherichia coli, 1 Serratia marcescens, 1 Pseudomonas aeruginosa). Patients were given orally 200 mg 12 hourly. Treatment duration went on from 2 to 6 months. In this trial, the evaluation was successful in the 10 cases with a delay of 2 to 13 months (m 8,9) after the end of the treatment. Prosthetic material has been taken off in 1 case out of 4 patients (prosthetic hip) because of persistaet free bacteria outflow. For one patient, a superinfection with a Pseudomonas aeruginosa resistant to ofloxacin was noticed at the second month. Bone levels (microbiological method) were between 1,3 and 9,7 mg/l and always higher to the MIC of the bacteria. Biological tolerance was satisfactory in spite of a rise of transaminase level, a transient renal disfunction whom relationship to the treatment was difficult. 3 transient photosensitivities were also noticed.