Free and esterified cholesterol in the skin were assayed by gas chromatography after thin layer histochromatographic separation. There were 20 controls of both sexes, 36 subjects with type lla hyperlipoproteinemia, 27 with type IIb hyperlipoproteinemia and 19 with type IV hyperlipoproteinemia. Esterified skin cholesterol levels were higher in women with the type of lla disorder and in subjects with tendinous xanthomas. The levels of esterified skin cholesterol in type II women is not correlated with free skin cholesterol or with total circulating cholesterol; all these parameters are correlated in men. Furthermore, skin cholesterol levels were determined in 15 type II subjects before and after a six month treatment with the anticholesterolemic probucol. Cholesterolemia decreased 10 per cent, free skin cholesterol decreased slightly and esterified skin cholesterol increased significantly, as did the esterified/total skin cholesterol ratio. These data suggest the existence of a relationship between low vascular risk and elevated levels of esterified skin cholesterol (or elevated esterified/total skin cholesterol ratio).