This retrospective study investigated the causative pathogens, complications, and outcome of 58 children who were hospitalized for septic arthritis at a tertiary care hospital in southern Taiwan from July 1988 to December 2000. The mean age was 3 years (range, 12 days-16 years). The males/females ratio was 1.2:1. Ninety percent of the cases involved lower extremities (knee, hip, and ankle) with the hip being the most common site of infection (54%). Joint pain (81%) was the most common clinical presentation, followed by fever (74%), local warmness and swelling (72%), and limitation of motion (64%). Erythrocyte sedimentation rate was elevated (> or = 20 mm/h) initially in 89% of the cases. The predominant causative organism was Staphylococcus aureus (43%, 25/58), 6 isolates of which were methicillin-resistant, followed by coagulase-negative Streptococcus (6), Streptococcus pneumoniae (3), Salmonella spp. (3), Haemophilus influenzae type b (2), and group B Streptococcus (2). The concomitant complications of septic arthritis were sepsis (9%, 5/58) and meningitis (2%, 1/58). Ten patients had sequelae, including limitation of motion (6), limping gait (2), limb-length discrepancy (1), and abnormalities of bone growth (1). This study found that S. aureus was the most common infecting microorganism in septic arthritis in children. Septic arthritis with concomitant osteomyelitis and infection due to methicillin-resistant S. aureus was associated with a significantly increased risk of sequelae (relative risk, 46.4, 95% CI, 2.9-748.8; relative risk, 16. 2, 95% CI, 1.3-204.9, respectively).