Background: We have previously shown that mitral valve reconstruction in infants and children allows somatic and valve growth, delays or eliminate the need for future valve replacement. This study evaluates our technique of stabilizing the posterior annulus with untreated autologous pericardial strip to determine whether it allows growth of anterior mitral valve leaflet and its annulus. Methods: Seventeen children (mean age 9.76±5.8 years) were prospectively followed-up after mitral valve repair for congenital mitral insufficiency with severe annular dilatation and anterior mitral leaflet prolapse. Repair techniques were Paneth posterior annuloplasty (n=14) and Gerbode plication plasty (n=3), both modified with stabilization of the posterior annulus with untreated autologous pericardial strip. Echocardiograms and motion studies of the anterior mitral valve leaflet were taken perioperatively and serially during follow-up. Results: Serial Doppler echocardiographic studies showed good valve function at a mean follow-up of 11.3±1.5 years. Transmitral flow indices were normal (3.7±cm2/m2) and mean flow velocity peak was 1.06±0.2 m/s. Diameter of anterior leaflet and its annulus increased linearly in relation to body size, seen consistently in all patients except two, who had reoperations for recurrent anterior leaflet prolapse and progressive mitral regurgitation, respectively. On reoperation, the untreated autologous pericardium was perfectly attached to the posterior annulus, covered by a smooth layer of fibrous tissue, without calcification. Conclusion: Stabilization of the posterior annulus with pericardial strip prevents further posterior annular dilation, allows anterior leaflet and its annulus to grow in relation to body size over time preserving the flexible properties of the mitral valve orifice.