Twenty-seven patients (mean age 72 years) with symptoms of congestive cardiac failure who had been controlled by treatment with 1 to 2 tablets per day of a combination preparation of frusemide (40 mg) and amiloride (5 mg) for at least 12 weeks were studied. The study was designed to assess the efficacy and tolerability of continuing treatment with the combination for a further 9 months, i.e. a total period of 12 months. Assessments of disease status and laboratory data were made every 3 months. Reasonable control of symptoms was achieved over the 12-month period although the majority of patients did not show a clinically important change. Some overall trends towards increasing oedema, dyspnoea and orthopnoea were observed as the study progressed, but these changes were not regarded as unusual considering the patients' age group. Significant increases in pulse rate and decreases in blood pressure were demonstrated, suggesting that diuresis was maintained. The combination preparation was well tolerated without any reports of side-effects.