Five cases of septic prepatellar and 20 cases of septic olecranon bursitis are reported. All were men, with a mean age of 47 years. Seventeen had a history of recent trauma to the affected limb or sustained pressure on knees or elbows, or both, required by certain occupations. Septic bursitis was not associated with septic arthritis and could be easily distinguished from it by the characteristic bursal swelling and joint examination. Septic bursitis was misdiagnosed as nonseptic bursitis in eight cases despite characterstic bursal fluid leukocytosis (greater than 1000 cells/mm3) and recovery of bacteria on culture. Staphylococcus aureus was identified in 22 cases; 76% were resistant to penicillin. Intravenous antibiotics and bursal fluid drainage were uniformly succesful. Oral antibiotic ttherapy was also successful unless the infection was extensive or there was underlying bursal disease. Early recognition, prompt therapy, and preventive measures are necessary to reduce the morbidity of septic bursitis.