In 1986, the Committee on Safety of Medicines published a report suggesting that enalapril may have an adverse effect on renal function. The prescription event monitoring scheme subsequently published figures on adverse drug reactions and mortality for patients treated with enalapril. They concluded that enalapril did not have an adverse effect on renal function and survival. Similar data were not available for captopril, as the drug was marketed before prescription event monitoring had been developed. In the Department of Health and Social Security (DHSS) Hypertension Care Computing Project (DHCCP), 368 hypertensive patients treated with captopril and 371 treated with enalapril were followed for an average of 3.1 and 1.6 years, respectively. Thirty-two patients died; none had renal failure as an underlying cause of death. The death rate was similar in both drug groups, at 17.5 (enalapril) and 24.0 (captopril) per 1000 patient-years. The present report shows that, for patients treated for high blood pressure, the relative risk of mortality with captopril compared with enalapril was 1.37, an insignificant difference (95% confidence interval 0.63, 2.98).