Total serum cholesterol, free and esterified cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, serum triglycerides and serum lipoproteins were measured in 103 consecutive cancer patients (60 men and 43 women; mean age, 56 years) and 100 age-matched noncancer inpatients. Cancer patients as a group demonstrated significantly lower total cholesterol, esterified cholesterol and LDL cholesterol, compared with noncancer patients. Breast cancer proved to be an exception associated with increased serum total cholesterol, free cholesterol, LDL cholesterol, and triglycerides. a-lipoproteins were constantly increased in cancer patients whereas no differences were found in the other lipoprotein fractions. Finally, the observed overall incidence of hyperlipidemia in cancer patients (23/103) was not significantly different from the controls (29/100).