Twenty-five cases of polyarticular septic arthritis (PASA) were observed in our department over a 13-year period. They accounted for 16.6% of all septic arthritis (15% on average in the literature). A male predominance was noted in our patients, as well as in the literature. The knee was the most frequent location followed by the elbow, shoulder, and hip, in varying order depending on the series. An average of 4 joints was involved. The causative microorganism was Staphylococcus aureus in 20/25 of our patients and in about 50% of published cases. Other frequently causative organisms were streptococci and gram-negative bacteria. Blood cultures and joint aspirations were positive in 19/22 and 23/25 of our cases, respectively. Other septic lesions were noted in 10/25 of our cases. Fever and severe leukocytosis were absent at admission in 5/25 (literature, 37%) and 10/25 of our 25 patients, respectively. The underlying disease was rheumatoid arthritis in 13/25, while 9 of the other patients had immunodepression caused by drugs or by concurrent illness. Typically, rheumatoid arthritis was long-standing and erosive, patients having ulcerated calluses on the feet. This skin source was also noted in 23/36 published cases of PASA in rheumatoid arthritis. Systemic lupus erythematosus was an uncommon disease in PASA, but its presence promoted gram-negative infection. Despite effective therapy with 2 antibiotics, 8/25 patients died, a prognosis that is equally severe in cases reported in the literature (30%) and one that has remained surprisingly stable over the last 40 years. For comparison, the death rate was only 4% in our patients with MASA. Factors contributing to a poor prognosis were age greater than 50 years, rheumatoid arthritis as an underlying disease, and disease of staphylococcal origin. Septic polyarthritis should be considered even when the clinical picture is not florid--when patients have low fever and normal white blood cell counts. Nor should the simultaneous involvement of distant joints rule out infection. Indeed, the frequency of underlying rheumatic disease and its treatment may further confuse the clinical presentation. Joints suspected of harboring infection should be aspirated, including those previously affected by the concurrent rheumatism.