Since atherogenesis may begin in childhood, and elevated serum lipoprotein(a) (Lp(a)) concentrations increase cardiovascular risk, we explored the early expression of the apolipoprotein(a) (apo(a)) gene and relationships between infants' and parents' serum levels. In a consecutive series of 1032 babies aged 3-5 days the distribution of apo(a) levels was positively skewed as in adults but with lower levels: 50th and 95th percentiles were the equivalent of 30 mg/l and 130 mg/l of Lp(a) in serum. Concentrations were re-measured in 51 infants when aged 8.5 +/- 2 months together with parental values. Levels at 3-5 days and 8.5 months were highly correlated (r = 0.73, P < 0.0001, n = 51) with a twofold increase at 8.5 months. Regression coefficients between 8.5 months concentrations and those of fathers, of mothers and the average level of both parents were 0.439, 0.521 and 0.93, respectively (P < 0.0001 for each), and infant and parental levels were then not different. The positive and negative predictive values of first post-natal week capillary blood apo(a) measurements detecting a parent with serum Lp(a) above 300 mg/l were 95% and 70%. We conclude that the apo(a) gene is virtually fully expressed before 1 year during which apo(a) levels track closely and are predictive of parental values. Childhood Lp(a) measurements may identify families at enhanced cardiovascular risk and facilitate targeted prevention.