A study of coronary risk factor relationships was carried out in 213 families with adolescents in Geelong, Victoria, Australia, in 1987. Weight, height, skinfold thicknesses, body circumferences, blood pressure and serum cholesterol were measured in both parents and children and other relevant information was obtained by questionnaire. The study group did not differ significantly from the Geelong population with respect to the proportion of Australian-born parents but contained a significantly higher proportion than expected of fathers who had a university degree or diploma. Twenty-five per cent of adolescents, 30% of mothers and 38% of fathers were positive for at least one of the three major established coronary risk factors. Significant correlations between parents and children, but not between parents, were found for total cholesterol and systolic blood pressure, while significant correlations were observed both between parents and children and between parents for measures of body size, body fatness and body fat distribution. The strongest predictors of risk factor status in adolescence were both parents with total cholesterol at or above 5.5 mmol/l, one or more parents who smoked and one or more grandparents with a history of coronary heart disease. Body mass index in adolescence was unrelated to heart disease risk factor status in adolescence or to a family history of heart disease. During early childhood and adolescence, parental risk factor status, rather than anthropometric or risk factor screening of the children themselves, is likely to provide the best guide to those at risk for an adverse coronary risk factor profile.