Serum lipid and lipoprotein values of 32 male patients suffering from gout were quantitated and compared with corresponding values of a random control group which did not differ significantly with regard to age, body weight index and socio-economic status. All patients were on therapy with allopurinol which lasted on average for 6 years. The most striking differences between patients and controls were the increased triglyceride and apo B values and the decreased HDL-cholesterol (HDL-C) and HDL-phospholipid (HDL-PL) values in the patient group. The values of total cholesterol, LDL-cholesterol, apo A-I and Lp (a) were not significantly different between patients and controls. The great differences in the ratios of apo B/LDL-C, apo A-I/HDL-C and apo A-I/HDL-PL values suggest that gout is connected with changes in the chemical composition of the major lipoprotein classes. In three normolipemic individuals who were treated for 3 weeks with allopurinol no changes in lipoproteins and apolipoproteins were apparent. The results are discussed in view of the atherosclerosis risk of patients suffering from gout.