In this study, we attempted to determine the prevalence of tobacco or nicotine dependence in current smokers in Japan and to assess the relationship between alcoholism and tobacco or nicotine dependence. The subjects consisted of 246 alcohol-dependent and 1,111 non-alcohol-dependent individuals. We used a questionnaire, consisting of items obtained from the World Health Organization's The ICD-10 Classification of Mental and Behavioural Disorders: Clinical Descriptions and Diagnostic Guidelines (ICD-10) and the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) criteria for tobacco or nicotine dependence. The prevalence of tobacco dependence diagnosed according to the ICD-10 criteria was 23.9% among all subjects. The prevalence of tobacco dependence diagnosed according to the ICD-10 criteria was higher in alcohol-dependent individuals (58.1%) than in nondrinkers or social drinkers (12.8%). Alcohol-dependent subjects consumed significantly more nicotine per day than did nondrinkers or social drinkers. The prevalence of nicotine physical dependence diagnosed by using DSM-IV criteria for nicotine withdrawal was 2.4% in alcohol-dependent individuals, whereas only 0.3% of nondrinkers or social drinkers exhibited nicotine physical dependence. These results indicate to us that the potential for nicotine physical dependence is not much stronger than that reported among current smokers.