The dietary guidelines developed for adults have been extended to children, but the role of serum cholesterol in the neurodevelopment of children is poorly understood. In the Third National Health and Nutrition Examination Survey (1988-1994), serum total cholesterol was measured in 4,852 children aged 6-16 years. Psychosocial development was evaluated by interviewing the mother regarding the child's history of school suspension or expulsion and difficulty in getting along with others. After adjustment for family socioeconomic status, maternal marital status and education, children's nutrition, and academic performance, the odds ratios of children with various concentrations of total cholesterol showed the children to be equally comfortable in their own peer subculture and not to be different in the proportion that had seen a mental health professional. However, non-African-American children with a serum total cholesterol concentration below the 25th percentile (<145 mg/dl) were almost threefold more likely to have been suspended or expelled from schools than their peers with total cholesterol at or above the 25th percentile (odds ratio = 2.96, 95% confidence interval: 1.55, 5.64). The authors concluded that, among non-African-American children, low total cholesterol is associated with school suspension or expulsion and that low total cholesterol may be a risk factor for aggression or a risk marker for other biologic variables that predispose to aggression.