Objective-This study investigated the frequencies of insomnia and its self-medication with alcohol in a sample of alcoholic patients, as well as the relationship of these variables to alcoholic relapse.Method-Subjects were 172 men and women receiving treatment for alcohol dependence. They completed a sleep questionnaire, measures of alcohol problem severity and depression severity, and polysomnograpy after at least two weeks of abstinence.Results-Using eight items from the Sleep Disorders Questionnaire, >60% of subjects were classified as having symptomatic insomnia during the six months prior to treatment entry. Compared to patients without insomnia, patients with insomnia were more likely to report frequent alcohol use for sleep (55% vs. 28%; χ 2 =12.03, df=1, p=0.001), had significantly worse polysomnographic measures of sleep continuity, and had greater severity scores for both alcohol dependence and depression. Among 74 alcoholics who were followed a mean of five months after treatment, 60% with baseline insomnia vs. 30% without baseline insomnia relapsed to any use of alcohol (χ 2 =6.16, df=1, p=0.02). Insomnia remained a robust predictor of relapse after applying logistic regression analysis to control for other variables. A history of self-medicating insomnia with alcohol did not significantly predict subsequent relapse.Conclusions-The majority of alcoholic patients entering treatment reported insomnia symptoms. Given the potential link between insomnia and relapse, routine questions about sleep in clinical and research settings are warranted.