The influence of diets enriched in a mixture of conjugated linoleic acid (CLA) isomers (CLAmix) and/or selenium as Na₂SeO₃ (SeIV) or selenized yeast (SeY) on feed intake, kidneys’ weight and the concentrations of fatty acids (FA) in the kidneys of rats was investigated. The study was performed on 80 female Wistar rats (Hsd Brl Han: WIST), 8 weeks of age with an initial body weight of 195.7±0.8 g. Each group numbered 8 rats. During the 7-day preliminary period the rats were fed a standard Labofeed H diet at a sub-maintenance level. Next, for 6 weeks the rats were fed ad libitum on the experimental diets supplemented with CLAmix, 0.2 ppm Se or 0.5 ppm Se as SeIV (_LSeIV or _HSeIV, respectively) and SeY (_LSeY or _HSeY, respectively). The rats were sacrificed at the end of the six-week experimental period. The diets enriched in CLAmix or Se (as SeIV or SeY) showed a negligible effect on kidneys’ weight, although the diets containing simultaneously CLAmix and Se numerically increased kidneys’ weight compared with the control animals. The addition of CLAmix to the diet, regardless of the higher level of SeY, showed a tendency to decrease in feed intake and decreased the concentrations of saturated (SFA), mono- (MUFA) and polyunsaturated (PUFA) fatty acids in comparison with the control rats. Dietary SeIV or SeY, irrespective of the concentration of extra Se, decreased the concentration of unsaturated fatty acids (UFA) and the sum of all assayed fatty acids (ΣFA) in the kidneys. The diet containing CLAmix and Se as _HSeIV or _LSeY decreased the concentrations of SFA, MUFA and PUFA in the kidneys compared with the control rats. On the other hand, the addition of _LSeIV or, especially, _HSeY to the diet enriched in CLAmix resulted in an increasing in the concentrations of SFA, MUFA and PUFA in the kidneys compared with the control group and rats fed the diets containing CLAmix, SeIV or SeY. The diet enriched in CLAmix and HSeY most effectively stimulated the accumulation of CLA isomers with the exception of cis11trans13CLA in the kidneys in comparison with other diets. Dietary CLAmix decreased the capacity of Δ9-desaturase in the kidneys compared with the control rats. The addition of SeIV or SeY to the diet increased the capacity of Δ4-desaturase, while the diet containing CLAmix with or without Se as SeIV or SeY increased the capacity of Δ4- and Δ5-desaturase in the kidneys compared with rats fed the diet with extra Se or the control diet. The present studies documented that dietary CLAmix resulted in decreasing in biosynthesis of fatty acids in the kidneys, while the diet with CLAmix and _HSeY most significantly stimulated the accumulation of SFA, MUFA and PUFA and long-chain PUFAn-3 and PUFAn-6 in the kidneys.