Over a 5 year period we have operated on 55 patients with endomyocardial fibrosis (EMF). The patients were from 4 to 56 years old (mean 13) and they were usually in poor condition at the time of surgery, with 47% in class III, and 24% in class IV with respect to cardiac function. They presented with right heart restrictive diastolic filling pattern (n = 17), mitral insufficiency (n = 18), or a combined syndrome (n = 20). All patients were operated upon during cardiopulmonary bypass and were submitted to a combination of the following procedures: endocardiectomy (30 right ventricular, 28 left ventricular), valvular replacement (21 tricuspid valve, 27 mitral valve), and/or valvuloplasty (10 mitral, five tricuspid). Nine patients, all with left ventricular or bilateral EMF, died in the postoperative period (16%), mainly of low cardiac output. There were five late deaths (three valve related). All other patients were functionally improved at the mean follow-up of 32 months. Twenty-two underwent a late catheterization study. We conclude the following from our experience: EMF is a very severe disease that is seen mainly in childhood and adolescence, carries a poor spontaneous prognosis, and is frequently seen in tropical countries. Surgical treatment is beneficial, but surgical mortality is high. Our technical modifications have totally eliminated the occurrence of postoperative complete heart block. A conservative valvular procedure has been shown to be possible even in some patients with severe mitral insufficiency and left ventricular EMF. The late objective improvement is better in those with left ventricular EMF than in those with right ventricular EMF.(ABSTRACT TRUNCATED AT 250 WORDS)