Two hundred and thirty-three patients (66 males and 167 females), aged 24 to 92 years, with congestive cardiac failure were entered into a long-term study to evaluate the efficacy and tolerability of treatment with a fixed dose combination tablet containing 1 mg bumetanide and 5 mg amiloride. One hundred and fifty-five patients were treated for 52 weeks. The daily dosages were 1 tablet (113 patients), 2 tablets (35 patients), 3 or 4 tablets (7 patients). Treatment was associated with a marked reduction in the prevalence of ankle oedema, dyspnoea and pulmonary crepitations, and with statistically significant decreases in body weight, pulse rate and calf measurement. Mean serum potassium showed a small but statistically significant increase, but serious hyperkalaemia was not encountered. Although serum sodium decreased, serious hyponatraemia did not occur. No clinically significant effects on hepatic, renal or haemopoietic function were observed. Minor adverse effects, most of which resolved spontaneously, were reported by 60 patients. Only 14 (6.0%) patients ceased treatment because of adverse effects.