This study was carried out to identify patients with Chagas' disease at risk of sudden cardiac death, inasmuch as such patients have not been recognized thus far. Seventy-four consecutive patients with a positive complement fixation test for Chagas' disease prospectively followed up at the Cardiomyopathy Clinic from January 1990 to June 1993 were entered into the study. Patients underwent medical history, physical examination, serological tests, resting electrocardiography, chest X-ray and two-dimensional echocardiography. Eighteen of 74 (24%) patients died during the study period, 8 (10%) suddenly and 10 (14%) from pump failure. Sudden death comprised 44% of total deaths. In the univariate model, cardiomegaly in the chest X-ray, left ventricular systolic and diastolic dimension, left ventricular ejection fraction, left atrial dimension and apical aneurysm as detected echocardiographically, and systolic blood pressure were associated with sudden cardiac death. In the multivariate model, however, apical aneurysm and left ventricular diastolic dimension were retained as predictors of sudden cardiac death. We conclude that chagasic patients with apical aneurysm and left ventricular dilation are at risk of sudden cardiac death.