OBJECTIVE To study the level of lipoprotein(a)--Lp(a) in the blood serum and incidence of isoforms of apolipoprotein(a)--apo(a) in males and females with cholelithiasis and free of it in population of Novosibirsk; to assess possible correlations between Lp(a) level in the blood, apo(a) isoforms and bile lithogenicity in females with cholesterol cholelithiasis. METHODS Examination of the representative samples of 870 females aged 25-64 years and 405 males aged 35-54 years has detected cholelithiasis in 91 females and 19 males. RESULTS Serum levels of Lp(a) are associated with cholelithiasis. Risk of the latter in males (Lp(a) > 28 mg/dl) and females (Lp(a) > 24 mg/dl) is estimated. It is confirmed that isoforms of apo(a) B, S1 and S2 in females and isoforms of apo(a) B, S2 in males with cholelithiasis occur much more frequently than in individuals free of cholelithiasis while isoform apo(a) S4 is rare. Females with cholesterol cholelithiasis have positive correlation between blood Lp(a) levels, the presence of isoforms apo(a) B, S1 and bile lithogenicity. CONCLUSIONS Males and females with cholelithiasis have more frequent high concentrations of Lp(a) (> 30 mg.dl) while low levels (0-5 mg/dl) are rare. There is a correlation between blood levels of Lp(a), apo(a) isoforms, bile lithogenicity in females with cholesterol cholelithiasis.