A retrospective medical record-based study of cases of peripheral pyogenic arthritis diagnosed in a rheumatology department between 1966 and 1993 was conducted. Of the 197 cases, 179 were evaluable. Pyogenic arthritis accounted for 0.68% of admissions and 30.3% of bone and joint infections during the study period. Incidence rose gradually from 2.2 new cases per year between 1966 and 1970 up to 6 to 10 new cases per year since 1991. In 88% of cases a single joint was involved, with the most commonly affected sites being the knee (32.5%), hip (22.2%), shoulder (12%) and sacroiliac joint (11.4%). Of the 22 patients with polyarticular arthritis, 19 had involvement of two joints. A portal of entry was identified in 53% of cases. Of the 13% of iatrogenic cases, half occurred after a local corticosteroid injection. The pathogen was identified in 65% of cases. Staphylococcus aureus was the most common organism (56%) followed by streptococci (9.5%) and E. coli (7%). Only three patients had gonococcal arthritis. Mean duration of therapy was four months. Although complications were exceedingly rare, three patients died and three others developed septic shock. Our data suggest that the presentation of pyogenic arthritis has remained essentially unchanged. In particular, we found no increase in iatrogenic forms, in contrast to recent experience with vertebral osteomyelitis.