1. 1. Two-year-old salmon were fed for 8 months with three diets with small, but significant, differences in lipid content and fatty acid composition. 2. 2. The fatty acid composition in abdominal fat, red muscle, white muscle, liver and heart of the fish was determined at the end of the feeding period by a chemometric method. 3. 3. The fatty acid composition of all tissues differed from that of the diets, least in the abdominal fat, most in the liver and heart tissue. 4. 4. The fatty acid composition of the tissues, the heart tissue in particular, was independent of the fatty acid composition of the diets. 5. 5. Large differences in the fatty acid compositions were observed between different fish. 6. 6. The advantage of multivariate interpretation of fatty acid compositions is demonstrated. © 1990.