An apparent protective effect of light-to-moderate alcohol consumption on the risk of coronary heart disease has been documented in numerous ecological, case-control and cohort studies. The findings are consistent and there are several biological effects of alcohol which could explain the findings. It has been argued, however, that the observed association is an artefact due to either the misclassification of ex-drinkers as never-drinkers or to confounding factors. A series of recent studies have addressed these concerns and examined the possible biological mechanisms involved. These studies add support to the hypothesis that the inverse association between light-to-moderate alcohol consumption and coronary disease risk is causal. Increasing consumption offsets the benefits for coronary heart disease with adverse health effects: epidemiological evidence indicates that safe limits are up to two to three drinks a day for men and one to two drinks a day for women.