Two methods are described for enlarging the aortic and mitral valvular annuli. The first method is aortoventriculoplasty, the results of which are reported here in 7 patients with small aortic annulus and in 4 cases with stenotic aortic valvular prosthesis inserted previously. The second method is developed for enlargement of the mitral ring to insert larger mitral valvular prosthesis. In this method the aortic and mitral annuli are split through a conventional incision and patched after mitral and aortic valve replacement with larger prostheses are done. This method is used in an 8-year-old boy with success. Both methods have proved to be useful especially in children and the results are very encouraging so that they could be accepted in the repertoire of the cardiac surgeon.