We studied 33 patients with dilative cardiomyopathy to evaluate the predicting factors for sudden death occurring within one year. The information on each of the patients included history, physical examinations, two-dimensional echocardiograms, 24-h ambulatory electrocardiograms, and cardiac catheterization or autopsy. Patients were followed up for one year. Univariate analysis showed maximum number of premature ventricular complexes per hour (PVCs/h) (p = .0012), maximum beats per episode of ventricular tachycardia (VTmax) (p = .0012), and left ventricular end-diastolic pressure (p = .046) to be significant prognostic risk indicators of sudden death within one year. To select the best combination of factors that predict sudden death, multivariate stepwise logistic regression analysis was performed. By this method, only PVCs/h and VTmax were selected as the best combination. Probability of sudden cardiac death within 1 year = 1/(1 + exp[6.65-1.78 (log PVCs/h)-0.71 (VTmax)]). The equation showed 85.7% sensitivity and 69.2% specificity at a probability cutoff point of p = .124, with accuracy of 72.7%. The incidence of sudden death was 80% in patients showing both frequent (greater than 100/h) PVCs and presence of VT (VTmax greater than or equal to 3), and 6% in patients with neither or both. We concluded that PVCs/h and VTmax are independent and significant prognostic factors in patients with dilative cardiomyopathy.