Children whose parents had early coronary heart disease were investigated for lipid abnormalities. In order to assess high risk parameters and the efficacy of the applied care, serum total cholesterol (TC), total triglyceride (TT), total free cholesterol (FC) high density lipoprotein cholesterol (HDLC), high density lipoprotein free cholesterol (HDLFC), lipid peroxide (LP) levels, and lecithin: cholesterol acyl transferase (LCAT) activity were measured. Compared to a group of control children, the offspring of high risk subjects had increased TC, FC, and LP levels and decreased HDLC levels. After one year of preventative care all parameters normalized except the high FC level and elevated LCAT activity. The measurement of serum FC and LP levels seems to be a useful method for the determination of true high risk. The LCAT activity may show the efficacy of the dietary treatment.