The outcome and late results following mechanical valve replacement for various congenital lesions in pediatric patients were analyzed retrospectively. The study group comprised 44 children operated on at a mean (± SD) age of 8.9 ± 3.9 years (median 7.0 years) and followed up for a mean of 6.8 ± 3.5 years. The late mortality rate was 0.98% per patient-year. Three patients were reoperated on for patient-prosthesis mismatch. Thrombotic obstruction occurred in three patients (two in the tricuspid, one in the mitral position). Mechanical valves >23 mm diameter in the left systemic ventricle and >21 mm in the aortic orifice offer excellent long-lasting hemodynamic performance and a good long-term prognosis.