Recent data suggest that the protection against ischemic heart disease afforded by high density lipoprotein (HDL) cholesterol (C) may be concentrated in the HDL 2 subfraction. To examine the behavioral correlates of the HDL subfractions, we recalled 33 men and 17 women of a random sample from the Pacific Northwest Bell Telephone Company Health Survey. Adiposity and very low density lipoprotein (VLDL) triglyceride were negatively correlated with HDL 2 C. Smoking was not correlated with HDL 2 C, but was negatively correlated with HDL 3 C (men, r s = -0.635, p = 0.001; women, r s = -0.534, p -0.014); this relationship was independent of alcohol consumption, adiposity, and VLDL triglyceride. Alcohol consumption was also more strongly related to HDL 3 C (men, r s = 0.248, p = 0.082; women, r s = 0.586, p = 0.007). Lecithin cholesterol acyltransferase (LCAT) mass was negatively related with HDL 2 C, but was positively correlated with HDL 3 C and apolipoprotein A-ll. Smoking was negatively correlated with LCAT mass. Since it is believed that HDL 3 C is not associated with the risk of ischemic heart disease and since both smoking and alcohol consumption may mainly affect HDL 3 C, the current study suggests that the increase in risk of ischemic heart disease with smoking and the possible decrease with alcohol consumption may be mediated through mechanisms other than their effects on HDLC. (Arteriosclerosis 5:169-177, March/April 1985)