Commingling in the distributions of five lipids and lipoproteins was investigated in a sample of 567 Caucasians. Significant commingling was found for high density lipoprotein, low density lipoprotein, and very low density lipoprotein, but not for cholesterol and triglyceride. The differences between the present results and those reported earlier on a sample of Japanese-Americans are described and found to be partly attributable to differences in the sample sizes of the two studies.