Abstract Lipid composition of calf blood plasma, liver platelets, muscle, heart, and brain was measured, as affected by high dietary intake of linoleic acid from corn oil or of polyunsaturated fatty acids from fish oil concentrate. Plasma total lipids, phosphatidylcholine, and cholesteryl esters were reduced by corn oil and fish oil concentrate. Dietary fatty acid composition had no influence on percentage distribution of the major phospholipid components of liver, heart, muscle, and brain, but did alter the polyunsaturated fatty acid composition of major phospholipids in plasma, liver, platelets, muscle, and heart. In general, high linoleic acid intake increased linoleic acid and decreased oleic, arachidonic, and linolenic acids in tissue phospholipids, and fish oil concentrate high in eicosapentaenoic and docosahexaenoic acids increased phoslipid concentrations of these fatty acids. The fatty acid composition of brain phosphatidylcholine and phosphatidyl-ethanolamine was relatively resistant to dietary lipid alterations. The fatty acid changes in tissue phospholipids that resulted from dietary lipid alterations may have important implications in eicosanoid metabolism and in the structure and function of cell membranes.