Correlates of changes in total (TOTAL-C) and low density lipoprotein cholesterol (LDL-C) were examined in the 3806 hypercholesterolemic men of the Lipid Research Clinics Coronary Primary Prevention Trial. These correlates included changes in weight, dietary and alcohol intake, plasma glucose and thyroxine, cigarette smoking, packet count, lipid-lowering drugs other than cholestyramine, and antihypertensive drugs. In both placebo plus diet and cholestyramine plus diet treatment groups, decreases in Quetelet index and in saturated fat and cholesterol intake and increases in polyunsaturated fat intake were consistently associated with reductions in TOTAL-C and in LDL-C. In the cholestyramine group, plasma glucose and smoking were predictors of increased TOTAL-C and LDL-C; age and packet count were predictors of decreased TOTAL-C and LDL-C. Diuretic use was associated with increases in TOTAL-C in both groups and with increases in LDL-C in the cholestyramine group.