We analyzed the effects of different types of dietary fat on the lecithin-cholesterol acyltransferase (LCAT) activity in 20 healthy women aged 26-49 years, consuming 6-week diets containing 54% of the calories as carbohydrates, 16% as protein and 30% as fat. The tested fats were successively: low erucic acid rapeseed (LEAR oil), sunflower oil, peanut oil and milk fats (butter and cream). The fractional and molar rates of LCAT were higher after sunflower and peanut oil diets and decreased significantly after LEAR oil and milk fat diets. The LCAT activity was independent of the P/S ratio of the diet, but positively correlated with the percentage of linoleic acid in serum phospholipids and cholesteryl esters, and negatively correlated with the percentage of oleic acid in the same fractions. Our results showed no relation between LCAT activity and the concentration of plasma cholesterol or triglycerides, no change in serum cholesteryl ester/total cholesterol ratio and confirmed that the distribution of high density lipoprotein subfractions is due to prerequisites other than LCAT.