Background Mitral valve (MV) reconstruction is the technique of choice for MV disease in infants and children. We evaluated whether our technique of posterior annulus stabilization with untreated autologous pericardial strip allows growth of anterior MV leaflet and its annulus. Methods Seventeen children (mean age, 9.43 ± 6.03 years; range, 1 to 17) were prospectively followed up after MV repair for mitral insufficiency with severe annular dilation and anterior mitral leaflet prolapse. The MV repair techniques were Paneth posterior annuloplasty (n = 14) and Gerbode plication plasty (n = 3), both modified with pericardial strip stabilization of the posterior annulus (Hetzer's modification). Echocardiograms were taken perioperatively and serially during follow-up. Results Serial Doppler echocardiography showed good valve function at mean follow-up of 13.62 ± 2.37 years. Left ventricular function was significantly improved, and mitral insufficiency was either absent or significantly decreased. Diameter of anterior MV leaflet and its annulus increased linearly in relation to body size. These findings were consistent in all patients except 3 who required reoperation 1 and 2 years postoperatively, respectively, for recurrent and progressive insufficiency. On reoperation, the pericardial strip was perfectly attached to the posterior annulus and covered by a fibrous tissues without calcification. Conclusions Stabilization of the posterior annulus with pericardial strip prevents further posterior annular dilation and allows anterior MV leaflet and its annulus to grow in relation to body size over time, as well as preserving flexible properties of the MV orifice.