Plasma cholesterol, triglyceride (TG) and high-density lipoprotein-cholesterol (HDL-C) were measured in a cross-sectional sample of 6,952 middle-aged Jerusalem residents in 1976-79, using the protocols and methods of the North American Lipid Research Clinics (LRC) prevalence studies. There were highly significant variations between groups of Jews of different origin. Age-adjusted levels of total cholesterol were about 10 mg/dl higher in European- and Israeli-born men and women than in immigrants from North Africa or Asia. TG levels showed a similar pattern in men, but the reverse in women. HDL-C levels were 2 to 4 mg/dl higher in European- and Israeli-born women than in female immigrants from Asia or North Africa. In men there was little variation of HDL-C by origin, but males showed significant ethnic differences in the proportion of HDL-C in total cholesterol, while females did not.