ObjectiveTo summarize the clinical characteristics and mid-long term efficacy of children under 15 years with mechanical valve replacement. Methods We retrospectively analyzed the clinical data of 51 children aged 1 to 15 years underwent mechanical valve replacement in Xinhua Hospital between January 2006 and January 2014. There were 32 males and 19 females with mean age of 9.6±4.0 years (ranged 1-15 years). ResultsThe average cardiopulmonary bypass time was 120.50±61.02 minutes, and average aortic cross-clamping time was 68.35±42.68 minutes. One patient died in hospital. There were 6 patients (11.8%) with complications including mitral paravalvular leakage in 1 patient, malignant ventricular arrhythmia in 1 patient, respiratory failure in 1 patient, acute renal failure in 2 patients, and delayed thoracic close in 1 patient. All the children cured and were followed up for 1-96 months. One patient died during the follow-up time. No other redo-valve replacement or complications correlated to anticoagulant occurred. ConclusionsMechanical valve replacement may be necessary in children with extremely dysplastic valves and severe hemodynamic impairment or after failed repair. With appropriate selection of the prosthetic valve and intensive care therapy during the peroperative period, the mid to long term efficacy is optimistic.