Previous reports have described an inverse relationship between alcohol consumption and the prevalence of myocardial infarction or the extent of coronary artery occlusion. The study reported here explored the relationship between patterns of alcohol intake and coronary occlusion in 526 patients who have had coronary arteriography. Patients were characterized as regular drinkers, occasional drinkers and non-drinkers. Regular drinkers were further characterized as drinking relatively consistent amounts or variable amounts. The inverse correlation between amounts of alcohol consumed and coronary occlusion found in previous studies was reaffirmed. It was also observed that the pattern of alcohol intake was related to the degree of occlusion. Higher levels of occlusion were found among non-drinkers, occasional drinkers, and regular drinkers with patterns of variable intake, while significantly lower levels of occlusion were observed for regular drinkers who drank relatively consistent amounts (P = 0.014). Furthermore, while occlusion scores were inversely correlated with amounts consumed by regular drinkers with consistent intake (P = 0.019), drinkers with variable drinking patterns had higher occlusion scores regardless of amounts consumed. Analyses of serum lipids according to drinking patterns showed a significant association between the total/HDL cholesterol ratio and drinking patterns. These findings suggest that whatever attenuating effect alcohol consumption might exert on coronary occlusion, it appears to be reversed by a variable or sporadic pattern of alcohol intake.