A restriction fragment length polymorphism (RFLP) at the low density lipoprotein receptor (LDLR) locus detectable with the restriction enzyme PvuII exhibits association with total serum cholesterol level. People who are homozygous for absence of the PvuII restriction site have a significantly higher total cholesterol level than heterozygotes (the number of homozygotes for presence of the restriction site was too small to permit meaningful comparison). This difference is significant at the 2% level. Thus, this study of sex- and age-adjusted cholesterol levels in a sample of healthy people yields additional evidence and sustains our previous proposal that normal alleles at the LDLR locus contribute to the population variation in total cholesterol levels. Absence of the PvuII site appears to confer an odds ratio of approximately 2.7 for having a cholesterol level in the top quartile of the population distribution.