Background The prognosis and quality of life of patients with advanced heart failure remain poor. The purpose of this study was to evaluate new nonpharmacologic approaches. Biventricular pacing was proposed in this indication, based on the encouraging results of acute hemodynamics studies. Methods Fifty patients with drug-resistant heart failure (New York Heart Association [NYHA] class III/IV, 16 of 34) were consecutively implanted with biventricular pacemakers. All patients had severe dilated cardiomyopathy and intraventricular conduction delay. Survival, NYHA class, electrocardiogram, echocardiographic data, and exercise tolerance were assessed over a mean follow-up period of 15.4 ± 10.2 months. Results At the end of follow-up, 55% of patients were alive without heart transplantation or left ventricular assistance device. The mortality rate was significantly lower in class III (12.5%) than in class IV patients (52.5%). In survivors, biventricular pacing significantly improved symptoms (NYHA class 2.2 ± 0.5 at follow-up vs 3.7 ± 0.5 at baseline) and exercise tolerance (^·VO₂ peak 15.5 ± 3.4 mL/min per kilogram at follow-up vs 11.1 ± 3 mL/min per kilogram at baseline). Conclusions Biventricular pacing appears to improve the functional status of patients with dilated cardiomyopathy with advanced heart failure. The technique appears to be attractive as an additive treatment, especially in class III patients. Controlled randomized studies are needed to validate this novel concept. (Am Heart J 2000;140:862-70.)