Monoarticular septic arthritis without disseminating sepsis occurred in 4 patients following renal transplantation. The septic arthritis was preceded by an infection with the same organism in an extraarticular location (3 urinary tract, 1 upper respiratory). All patients were on prednisone-azathioprine immunosuppressive regimen but none had granulocytopenia. Prompt antibiotic therapy resulted in quick resolution of the joint infection in 3 patients. Impaired host defenses, possible inadequate prior antibiotic therapy, and intrinsic joint alterations are potential contributing factors to the development of septic arthritis following renal transplantation.