Cross-sectional associations between self-reported hours of television (TV) viewing per day and cardiovascular risk factors were assessed in a biracial (black and white) study population of 4280 men and women, ages 23 to 35 years, undergoing the year-5 follow-up examination for the Cardiovascular Risk Development in Young Adults (CARDIA) study in 1990 to 1991. Number of hours of TV viewing per day was higher in blacks than in whites and was inversely associated with education and income. Relative to "light" TV viewers (0 to 1 h/d), "heavy" TV viewers (> or = 4 h/d) had a higher prevalence (P < 0.05) of obesity, smoking, and high hostility score in all race/gender groups, and of physical inactivity in all groups except black men. Among whites, "heavy" TV viewers had higher depression scores, and among blacks, reported more alcohol use. TV viewing was not associated with hypertension and lipid abnormalities. Heavy TV viewing is a modifiable behavior that is associated with increased prevalence of several cardiovascular risk factors.