We submit 3 cases of perforation of the mitral valve leaflet as a consequence of infectious endocarditis. In the first of this cases, perforation was the result of the impact of the regurgitant jet of an aortic insufficiency affected by bacterial endocarditis of the anterior mitral leaflet in a young female presenting various congenital malformations. Both the transthoracic and transesophageal echocardiography showed that the regurgitant jet affected the area where the lesions were later detected. In the other 2 cases the perforation appeared in valves previously affected by endocarditis. In these cases, only the transesophageal echocardiography showed the lesions. Surgery was performed in all 3 cases with satisfactory results, confirming the echocardiographical findings. We wish to emphasize the role of transesophageal echocardiography in the diagnosis of this rare process that may be the primary effect of the destructive action of the endocarditis, or a secondary effect, on dissemination by means of affected valves, on previously unaffected valvular leaflets.