We investigated the effect of oral ibopamine (SB 7505) on myocardial and renal function in eight patients suffering from congestive heart failure. Ibopamine was administered orally 50 mg twice a day for 7 days. Systolic time intervals PEP (preejection period) and EMS (electromechanical systole) decreased significantly after each administration of ibopamine. Maximum reduction of systolic time intervals was observed 4 h after ibopamine administration. Statistically significant shortening was still apparent at 8 h. Twenty-four hour urinary volume was greater than control values on each day of ibopamine administration. The average daily increase in urine output was 70.2%. Sodium and potassium excretion increased. Each patient showed symptomatic improvement during therapy. No side effects attributed to ibopamine therapy were observed, and clinical laboratory values were unchanged. Tachyphylaxis was not observed during the period of treatment. We conclude that oral administration of ibopamine improves cardiovascular performance and renal function in patients with congestive heart failure.