Summary: One hundred and sixteen senile patients (older than 65 years) with chronic heart failure (CHF) were analyzed retrospectively in order to verify if old patients with CHF would benefit from long-term (one year) angiotension-converting enzyme inhibitor (ACEI) treatment. The frequency of drugs (including ACEI, digitalis and diuretic) used was stratified into four degrees accordingly. Development of the CHF was scored with regard to relapse rate and severity of this disease. Stepwise regression analysis was applied to explore the relationship between the scored outcome of CHF and the frequency of individual drug administra tion. A significant relationship of the scored outcome of CHF to the frequency of ACEI usage but not to digitalis nor to diuretics was found (partial coefficient of the correlation r=0. 42, P=0. 002). It was concluded that the longterm administration of ACEI improves the outcome of CHF in senile patients.