Dietary linoleic acid enrichment in different plasma lipids was investigated in six healthy females. They were given formula diets (FD) containing no arachidonic acid, and providing a linoleic acid supply of 0% (FD0), 4% (FD4) or 20% (FD20) of total energy intake. At the end of each two weeks FD period fatty acid distribution was determined in cholesterol esters (CE) and in lecithin of LDL and HDL. The increase of linoleic acid in CE was twice that found in the lecithin of LDL and HDL. Comparing FD0 and FD20 the increase of linoleic acid in CE of LDL and HDL was 34%, and in lecithin 15%. Simultaneously oleic acid was lowered in CE (-17%) and in lecithin (-8%) of LDL and HDL. Comparing FD0 and FD20 arachidonic acid, which derives from linoleic acid, was lowered with increased linoleic acid intake in LDL-CE (-5%) and in HDL-lecithin (-8%), while no effect was found in LDL-lecithin. Our results demonstrate that dietary linoleic acid enrichment occurs preferentially in CE of LDL and HDL, but does not lead to an increase of arachidonic acid in plasma lipids. However, a decrease was found for arachidonic acid in HDL-lecithin, while in LDL-lecithin no effect could be observed. From this it is concluded that incorporation and metabolism of linoleic acid in different plasma lipids is not identical, although lipid exchange and lipid transfer have been shown for most lipoprotein fractions.