Twenty-three healthy males, aged 23 to 62 years, were examined by M-mode echocardiography and systolic time intervals for 3 h after (1) ethanol 1 g/kg by mouth taken over 60 minutes; (2) atenolol 100 mg by mouth; (3) ethanol (1 g/kg) + atenolol (100 mg). The peak mean blood ethanol (+/- s.e.) was 112 +/- 4 mg/100 ml in test 1 and 104 +/- 7 mg/100 ml in test 3. During increasing blood ethanol, heart rate (HR), systolic blood pressure (BP), cardiac output (CO) and echocardiographic indices of left ventricular (LV) function were significantly augmented, while total peripheral resistance (TPR) decreased. During declining blood ethanol, systolic BP, LV end-diastolic and end-systolic diameters, stroke volume (SV) and circumferential wall stress were significantly reduced; echocardiographic indices of LV function were unaltered, but the pre-ejection period/LV ejection time ratio was increased. Atenolol decreased HR, systolic BP, SV, CO, and all estimates of LV function, but increased TPR. Ethanol + atenolol tended to cause smaller depressions in the indices of LV function than did atenolol alone, in spite of similar plasma atenolol concentrations (n = 6). It is concluded that ingestion of modest doses of ethanol evokes vasodilation and enhances LV function during increasing blood ethanol, and reduces LV preload and afterload during decreasing blood ethanol without impairing contractility. Social drinking and beta blockade seem not to have any harmful acute combined effects on the heart and circulation, at least in normal subjects.