One hundred thirteen patients with 120 episodes of septic arthritis were seen during a 14-year period. The most common bacteria cultured from joint fluid or blood during the acute episodes were gonococci, staphylococci, and streptococci. Seventeen other bacteria were the infecting organisms in one or more cases each. Other infections and medical conditions frequently were present. In some instances the septic arthritis was a complication of another infection. In other patients septic arthritis appeared to occur because of diminished resistance to infection. The majority of patients responded well to medical treatment, but eight died and 26 had persistence of articular pain at follow-up examination.