Childhood acute septic arthritis is most often of hematogenous origin, and usually caused by Staphylococcus aureus. Characteristic symptoms and signs include a swollen, red painful joint, and fever. The diagnosis is confirmed by a joint aspiration. Following a brief 2- to 4-day intravenous phase, the antibiotic course is completed orally to a total of 10 to 14 days. Cephalosporins, clindamycin or staphylococcal penicillins, administered every 6 hours, are recommended as first-line antibiotics because of their appropriate spectrum, excellent penetration, good tolerability in large doses, and moderate price. Operative treatment (arthroscopy, arthrotomy) is not needed routinely, unless the response is tardy.