Hostility has been associated with coronary heart disease mortality. To assess possible mechanisms linking hostility to coronary heart disease risk, the authors conducted analyses in a cross-sectional study from data collected in 1985 and 1986 on 5,115 young adults, aged 18-30 years, black and white, male and female, in four large urban areas of the United States. The results show that higher levels of hostility as determined by the Cook-Medley Hostility Scale were strongly associated with tobacco and marijuana smoking, increased alcohol consumption, and greater caloric intake in both blacks and whites and in both men and women. The increased caloric consumption was evident in the higher waist/hip ratios, particularly in men (p less than 0.05). The associations were particularly strong (p less than 0.001) for tobacco cigarette smoking and marijuana smoking, with roughly a 1.5 times higher prevalence in the top hostility quartile compared with the bottom quartile after adjusting for age and education. Hostility levels were not related to the percentage of calories from fat or from sucrose intake, to plasma cholesterol levels, or to physical fitness (except for a weak association in the latter in white women). The results describe relations between hostility and health behaviors that may be detrimental to health. The findings provide a possible explanation for the association between hostility and coronary heart disease mortality.