The reference values for cholesterol concentrations in the whole serum and in its VLDL, LDL and HDL fractions have been produced based on the data obtained in the Mini-Finland Health Survey. The lipoprotein fractions were separated with ultracentrifugation. The aim was to obtain reference values for the apparently healthy, ambulatory population. Two health-derived criteria were used to select subjects for reference populations: those based on the literature available and those based on the recommendations published by the Committee on Reference Values of the Scandinavian Society for Clinical Chemistry and Clinical Physiology, with slight modifications. The 95% inner reference intervals of total serum cholesterol in all the subjects and in the two selection groups were 4.2-9.0, 4.2-8.4, and 4.2-8.5 mmol l-1 for men, and 4.2-9.4, 4.1-8.6, and 4.2-9.0 mmol l-1 for women, respectively. The corresponding medians were 6.3, 6.2 and 6.2 mmol l-1 in men, and 6.4, 6.0 and 6.1 mmol l-1 in women, respectively. Frequency distribution curves showed clear skewness to the right in VLDL cholesterol and slight skewness in LDL and HDL cholesterol. In women there was a clear rise in total, VLDL and LDL cholesterol after the early middle age, whereas HDL cholesterol was lower in the older age groups. In men the age dependency was not as prominent; total cholesterol levels showed lower levels in older men. Of the background lifestyle factors alcohol consumption, smoking, obesity and physical exercise had negligible associations with total, VLDL, LDL and HDL cholesterol reference intervals.