The influence of dietary conjugated linoleic acid (CLA) isomers (CLAmix) and/or Se as Na₂SeO₃ (SeIV) or selenized yeast (SeY) on the relative body weight gain (RBWG) of rats, pancreas weight, concentrations of CLA isomers and of other fatty acids (FA) in the pancreas were studied. For 6 weeks, female rats Wistar (aged 8 weeks) were fed ad libitum the Labofeed H diet enriched in 1.5% CLAmix, 0.2 ppm Se (_LSe), 0.5 ppm Se (_HSe) as SeIV (i.e. _LSeIV or _HSeIV, respectively), or SeY (i.e. _LSeY or _HSeY, respectively). Each group contained eight rats. The results documented that dietary _LSeIV and CLAmix most effectively increased the RBWG of rats and feed conversion efficiency, while the diet with _HSeIV most efficiently increased pancreas weight compared with the control rats. The diets enriched in CLAmix and Se as SeIV or SeY increased the sum of saturated fatty acids (SFA), the atherogenic SFA, A-SFA index, thrombogenic SFA (T-SFA), and the T-SFA index in the pancreas of rats compared with the control group. The diets containing CLAmix and Se as SeIV or SeY stimulated the accumulation of cis9trans11CLA, trans10cis12CLA, as well as the sum of all CLA isomers in the pancreas compared with rats fed the diet enriched in CLAmix. These diets increased the concentration of n-6 polyunsaturated FA (n-6 PUFA) and decreased the level of long-chain n-6 PUFA (Ln-6 PUFA) in the pancreas compared with the control rats and rats fed the diets with SeIV or SeY. The diets containing CLAmix and Se (as SeIV or SeY) increased the concentration of n-3 PUFA and Ln-3 PUFA in the pancreas compared with the control rats. Our study findings documenting that dietary Se and/or CLAmix and Se (as SeIV or SeY) considerably increased the concentration of PUFA, especially n-3 PUFA, improved the n-6 PUFA/n-3 PUFA ratio in the pancreas are valuable information for scientists carrying out research to improve animal and human health.