318 consultant physicians in Scotland were sent a questionnaire on their use of angiotensin converting enzyme (ACE) inhibitors to treat chronic heart failure (CHF). 229 (72%) replies were received. Of these 91% used ACE inhibitors for CHF; 22% were geriatricians, 58% general physicians and 20% cardiologists. All groups reserved ACE inhibitors for patients uncontrolled by diuretics alone. Compared to general physicians, cardiologists used ACE inhibitors in preference to other vasodilators and digoxin, used higher doses and commenced treatment more often on a day-patient basis. Cardiologists also commonly started treatment with captopril even if continuing with enalapril. Geriatricians used ACE inhibitors as frequently as cardiologists but at lower doses; they did not report side-effects more frequently. Further investigation of the safety and possible cost savings of supervised day-patient rather than in-patient, introduction of ACE inhibitors for CHF is now merited. To avoid an extended period of patient observation after the first dose of ACE inhibitor, captopril might also be given as the initial therapy, even if continuing with enalapril. This policy would also reduce the risk of any hypotensive response being prolonged.