In a prospective cohort of 181 individuals followed up since childhood - when aged 9, 12 and 15 years - patients with a family history of premature coronary heart disease (n = 18) had higher left ventricular mass index in adulthood - at mean age of 31 years - compared with those without (mean ± standard error 39.1 ± 1.9 versus 34.6 ± 0.7 g/m, p = 0.04). The correlation between adult left ventricular mass index and child triglycerides (r = 0.66, p = 0.04 versus r =- 0.03, p = 0.75; p = 0.02) and diastolic blood pressure (r = 0.65, p = 0.02 versus r = 0.16, p = 0.07; p = 0.05) was stronger among those with a family history of coronary heart disease than in those without. Although preliminary, these data suggest that the higher left ventricular mass index among adults with a family history might be explained by their increased susceptibility to child cardio-metabolic risk factors.