Background: Parental obesity and TV viewing are risk factors for childhood obesity. This study assessed the association of children's TV viewing and computer use with body mass and examined whether parental weight status modified the association. Methods: Cross-sectional associations of parental weight status, hours of TV viewing and computer use, and children's body composition were studied in a subsample of 526 black and nonblack children, aged 8, 11, and 14 years at baseline, enrolled in Project HeartBeat!, a longitudinal study of cardiovascular disease risk factors, 1991-1995. BMI, fat-free mass (FFM), and percent body fat (PBF) were calculated from children's body composition measured at baseline. Children's TV viewing and computer use habits and parental height and weight were self-reported. Multivariate regression analysis was used in assessing inter-relations of parental weight status and child's TV viewing and computer use habits with BMI, FFM, PBF, and risk for overweight status (BMI ≥85th percentile), adjusting for age, gender, race, and Tanner stage. Results: Children of one or two overweight/obese parents watched an average of 22±6 minutes or 30±11 minutes more TV per day than children of normal-weight parents, respectively (both p<0.01). In multivariate regression analyses, BMI and PBF increased significantly by 0.42 kg/m2 and 1.14% (both p<0.001), respectively, for each hour of TV watched among children with overweight parents, but not for those with normal-weight parents (pinteraction<0.05). Similar results were observed for total screen time. Conclusions: These study findings are consistent with a genetic contribution of parental weight; however, overweight/obese parents may also exhibit behavior patterns that negatively influence children's TV viewing and have an impact on child overweight status. The effect of parental BMI on children's BMI may have both a genetic and an environmental linkage.