These unhealthy behaviors, consistent with earlier studies, include drinking alcohol; consuming more than five alcoholic beverages in a row; using marijuana, cocaine, and smokeless tobacco; carrying weapons; physical fighting; sexual intercourse; failure to use a seat belt; lack of exercise; and consumption of fewer than five servings of fruits and vegetables daily. Although the findings do not establish causal links, they do show a consistent association between smoking and other unhealthy behaviors among adolescents, further strengthening the evidence that unhealthy behaviors among adolescents are interrelated. In almost all cases, current smokers had the highest and "never smokers" the lowest rates of other risk behaviors. The differences were particularly striking for use of other addictive substances such as alcohol, marijuana, and smokeless tobacco. Although not as dramatic, differences between smoking and nonsmoking teenagers were also noteworthy for carrying weapons, physical fighting, sexual intercourse, and failure to use seat belts. The interrelationships between smoking and other unhealthy behaviors are undoubtedly complex. Multivariate analyses are required to delineate the nature of these interrelationships. The data presented here suggest that high-risk behaviors may cluster. 3 tables and 17 references