A group of 28 patients with primary hyperlipoproteinaemia [19X lipoprotein (LP) type IIA, 8X type IIB and 1X a normolipidaemic patient with concurrent hyperapoB lipoproteinaemia] were given for a period of three weeks a dietetic preparation containing phytosterols - 12 g/day. This led to a significant drop of total cholesterol and LDL-cholesterol in plasma. The cholesterol concentration in HDL and both its fractions increased, the differences however were not significant. The triglyceride levels did not change. There was a significant drop of the apolipoprotein B (apo-B) concentration in LDL, the apo-A-I in plasma did not change. There was a significant drop of atherogenic indexes TC/HDL-C, LDL-C/HDL-C and apo-B/-A-I. During investigation of the LCAT activity the authors observed a significant rise of the fractional esterification rate associated with a highly significant drop of the free cholesterol concentration in plasma as a result of treatment. Discrimination analysis of parameters of the lipoprotein metabolism and the patients' body weight before treatment helps to assess a function by means of which it is possible in 92.3% of the subjects to predict the success of treatment before the administration of beta-sitosterol.