The effects of acute alcohol ingestion on the left ventricular performance of nine normal subjects, mean age 25 years, were studied before and after incomplete autonomic blockade, produced by atropine, 0.04 mg/kg body weight, and propranolol, 0.2 mg/kg body weight. Left ventricular (LV) function curves (stroke volume vs. end-diastolic volume) were plotted from data generated before and after large variations in cardiac preload. Increase in preload was produced by five degrees of head-down tilt for 90 minutes; decrease in preload was produced by graduated lower body negative pressure to -40 mmHg. After incomplete autonomic blockade, the negative inotropic effects of acute alcohol ingestion were minimal but significant and manifest by the reduction in mean velocity of circumferential fiber shortening (p less than 0.05). Studies during wide variations in preload confirmed the importance of maintaining central blood volume after alcohol ingestion. Lower body negative pressure after both incomplete autonomic blockade and alcohol produced a further deterioration in mean velocity of circumferential fiber shortening (p less than 0.05).