Ninety-four children ranging from 3 months to 19 years of age underwent cardiac valve replacement at Columbia Presbyterian Medical Center from 1965 to 1985. The overall operative mortality was 12%, but mortality was higher among patients less than 2 years of age, patients who had had previous cardiac operations, and patients requiring double-valve replacement. Seven of 11 patients who received mechanical valves and no anticoagulation experienced major thromboembolic events. An episode of gastrointestinal hemorrhage that was easily controlled represents the only bleeding complication in the entire series. Valve replacement in children continues to be a high-risk procedure, and efforts to preserve native valve function should be attempted when technically feasible. Our data also suggest that anticoagulation can be safely accomplished in the pediatric age group and should be employed in patients requiring placement of a mechanical prosthesis, especially in the mitral position.