Few studies have considered whether the habitual use of tobacco in Southeast Asia is part of an established pattern of addiction that includes regular alcohol use. As part of a national survey of adult tobacco use in Cambodia (n = 13 988), we found that men who smoked were 2 times more likely to have drank alcohol in the past week (odds ratio = 2.53, 95% confidence interval = 2.10-3.03). By age 18 to 25 years, 47% of male smokers drank alcohol, and this pattern of alcohol and tobacco use increased to >55% through the fifth decade. Women using smokeless tobacco with betel quid were more likely to be alcohol drinkers (odds ratio = 1.49, 95% confidence interval = 1.12-1.98). Past week’s drinking declined by late middle age and was associated with lower education and being currently married; the behavior was lower in some ethnic groups (ie, Cham). Our findings indicate an important association between alcohol and tobacco use, and raise the possibility that reducing alcohol consumption can be an important component of tobacco control.