The duration of treatment and appropriate guidelines for antibiotic prophylaxis for children with poststreptococcal reactive arthritis (PSRA) have not been determined. The authors performed a retrospective chart review of 40 children with PSRA and examined their clinical features at initial evaluation and at 6, 12, and 24 months. At baseline, 18% (n = 7) had a finding noted on the echocardiogram. Although most patients developed cardiac findings early on in the course of their disease, 2 patients with a normal baseline echocardiogram may have developed findings after 12 months of follow-up. The mean duration of prophylaxis was 22 months. During the follow-up period, there was improvement in Physician's Global Assessment, number of patients with arthralgia, tender and swollen joints, erythrocyte sedimentation rate, anti-streptolysin O, and anti-DNAse B antibody titers. The authors conclude that marked improvement in clinical features and laboratory values was seen over time. Patients may benefit with long-term cardiac follow-up.