Objective: We aim to report time-related outcomes following mitral valve replacement (MVR) in children and to identify factors affecting outcomes. Methods: Clinical records from 307 children who underwent MVR between 1985 and 2004 were reviewed. Competing-risks methodology determined time-related prevalence of three mutually exclusive end-states: death, mitral reoperation and survival without subsequent MVR, and their associated risk factors. Results: Mean age was 11.4 ± 5.6 years including 36 (12%) patients ≪2 years old. There were 154 (50%) males. Underlying pathology was rheumatic fever (n = 195, 64%), congenital (n = 83, 27%) and other (n = 29, 9%) with congenital pathology predominant in younger children while rheumatic fever predominant in older children. Hemodynamic manifestation was regurgitation (83%), stenosis (5%), or mixed disease (12%). One hundred and twenty-six patients (41%) had undergone a prior cardiac surgery including mitral surgery (n = 96, 31%). Initial mitral prosthesis was mechanical (n = 229, 75%), tissue (n = 71, 23%), or homograft (n = 7, 2%). Concomitant cardiac surgery was required in 141 patients (46%). Competing-risks analysis predicted that 20 years following MVR, approximately 17% of patients have died, 51% have undergone mitral reoperation and only 33% were alive and free from mitral reoperation. Risk factors for death without mitral reoperation included younger age ≪3 years [PE (parameter estimates): +1.66 ± 0.31, p ≪ 0.001], longer cross-clamp time (PE: +0.11 ± 0.04/10 min, p = 0.005), postoperative complications (PE: +1.58 ± 0.31, p ≪ 0.001), and higher prosthesis size/body surface area (BSA)-predicted mitral annulus ratio (PE: +0.48 ± 0.10, p ≪ 0.001). Risk factors for mitral reoperation included implantation of homograft or tissue prosthesis (PE: +1.12 ± 0.23, p ≪ 0.001) and smaller prosthesis size (PE: +0.06 ± 0.03/1 mm, p = 0.05). Fifteen-year freedom from pacemaker implantation, endocarditis, bleeding, and thromboembolism was 92%, 96%, 82%, and 92%, respectively. Conclusions: Mortality and mitral reoperation are common after MVR in children and outcomes can be predicted based on patient’s age, prosthesis size, and other associated factors. Some modifiable factors such as avoiding oversized prostheses may improve outcomes especially in the smallest children.