Turnover rates and metabolism in the legs and the splanchnic region of free stearic and oleic acid have been studied in five healthy male volunteers at rest and during bicycle exercise. A continuous infusion of 14C-labeled stearic acid and tritiated oleic acid was given intravenously. At rest, the fractional turnover was the same for the two acids; the fractional leg uptakes were also similar, while fractional uptake in the splanchnic region was 80% higher for oleic than for stearic acid. The response to exercise differed between the two acids: the arterial concentration of stearic acid fell, its fractional turnover and fractional leg uptake became higher than for oleic acid, and its fractional uptake in the splanchnic region increased, while that of oleic acid remained unchanged. It is concluded (1) that stearic acid turnover in the postabsorptive state is similar to that of the main part of the FFA fraction and (2) that the decrease in stearic acid concentration during exercise can be explained by an increased removal in excess of that for other FFA.