Dietary supplementation with conjugated linoleic acid (CLA) has been shown to reduce body fat mass. To investigate the effects of individual CLA isomers on the fatty acid profiles of lipogenic (liver and white adipose) and lipid sensitive (erythrocyte) tissues, BALB/c mice were fed with 1 of 2 diets supplemented with either a c9,t11-CLA-enriched and t10,c12-CLA-free or a CLA-mixture containing both isomers in equal amounts (1% w/w of the diet) for 5 weeks. A control group was fed with a diet enriched in sunflower oil to energy balance the CLA. Compared to the t10,c12-CLA-free and the control diets, we observed a significant reduction of adipose tissue accompanied by fatty livers in the CLA-mix-fed group. These alterations in body fat distribution entailed a conspicuous shift of the fatty acid profiles of adipose tissue and livers. Liver enlargement was mainly caused by accumulation of C18 monoenes that accounted for 67 ± 1% of total fatty acid methyl esters. The significant reduction of the 18:0/18:1 desaturation index in the liver upon CLA-mix diet indicated high stearoyl-CoA desaturase activity. In contrast, reduction in white adipose tissue was largely driven by percental reduction of monounsaturated fatty acids (p ≤ 0.001). 16:0/ 16:1 and 18:0/18:1 desaturation indices for white adipose tissue significantly increased, suggesting an inhibition of stearoyl-CoA desaturase upon CLA-mix diet. The fatty acid profile of the erythrocytes widely reflected that of livers, depending on the supplemented diet. These profound changes in fatty acid composition of lipogenic organs due to t10,c12-CLA intake may be the consequence of function- al alterations of lipid metabolism.