The status of cord blood screening of plasma lipids is reviewed, emphasizing the problems associated with the diagnosis of familial hyperlipoproteinemia (HLP), particularly type II (hyperbetalipoproteinemia), in the neonate. For 2937 neonates in this study the mean +/- standard deviation (SD) of plasma cholesterol was 70.3 +/- 16.9 mg/dl. The mean triglyceride level of 1805 neonates was 39.6 +/- 19.3 mg/dl. The mean level of beta-cholesterol in 240 neonates was 34.3 +/- 10.9 mg/dl and the correlation between total and beta-cholesterol was high (r=0.89). By convention, the upper limit of normal was defined as the mean + 2 SD, and these levels for total cholesterol, triglyceride and beta-cholesterol were 100, 80 and 55 mg/dl respectively. Only by careful follow-up of hyperlipidemic neonates can the incidence of HLP and the worth of early diagnosis be assessed.