During a 14 year period, 118 young patients between 9 and 20 years of age underwent mitral valve replacement. In view of the acknowledged advantage of durability and minimal thrombogenicity, we chose the Starr-Edwards valve prosthesis in the large majority of our subjects. Other prostheses have also been used. Hospital mortality has been only 3% in the past 5 years. Frail, severely incapacitated children and adolescents have had an impressive spurt in growth and weight and have returned to normal activities. Nine of the patients have had a normal pregnancy and have borne children. The remarkable clinical improvement has been corroborated by hemodynamic benefit. Follow-up over a period 1 to 15 years (mean 5.09 +/- 3.3) showed a very low incidence of embolic phenomena. In Third World countries, rheumatic heart disease continues to be a daunting challenge with pronounced disability resulting in death. Mitral valve replacement in the young subject with significant rheumatic valve disease should not be delayed until severe pulmonary vascular changes and myocardial damage pose a major deterrent.