Alcohol (0.5 g/kg bodyweight) was administered in two sessions and placebo in a third session to normal, healthy social drinkers. A control group was administered a mixer (i.e., no alcohol) for each of the three sessions. The heart rate and vagal tone index (V) response patterns were different to alcohol than to the mixer or placebo. The treatments did not differentially influence pulse transit time. The results indicated that the acute effect of a moderate dose of alcohol on the heart is parasympathetically (i.e., vagally) mediated and has no significant direct sympathetic component.