Serum lipid, lipoprotein(a) (Lp(a)), apolipoprotein (apo) A-I and B concentrations were studied in young families of Tallinn: 157 husbands, 81 wives and 149 newborns participated in the study; 48% of subjects were Estonians, 39% Russians and 13% other nationalities. As previous studies among middle-aged men and school children of Estonia revealed clear national differences in serum lipoprotein profiles, our special interest was to study lipoprotein parameters in relation to ethnic origin. Body mass index (BMI), blood pressure (BP) and smoking habits were determined. In newborns, maturity by physical and neurological criteria and Apgar score after birth were assessed. At the age of 18-30 years, Estonian men had significantly higher serum total cholesterol, LDL cholesterol, triglyceride and Lp(a) levels than did Russian men. Estonian newborns had higher serum triglyceride concentration than Russian ones. Among women no national differences were recorded in the measured parameters. Lp(a) levels were not statistically correlated with age, BMI, BP or current smoking. Negative associations were revealed between Lp(a) and serum level of apo A-I (in men) or triglycerides (in newborns). Lp(a) concentrations correlated positively with LDL cholesterol (in women) and apo B (in newborns). Lp(a) levels of newborns were not associated with birthweight or health status, but correlated strongly with the sum of parental and fathers' Lp(a) concentrations, demonstrating that a genetic factor(s) is involved in the values of plasma Lp(a) levels.