The effects of two different fat sources: saturat-ed-rich fat source (beef tallow) and n-3 rich PUFA fat source (Linseed oil) as well as a mix-ture (1:1) of both of them on broilers performance  and immune status have been studied. Four groups of broiler chicks (n=40) were fed on concentrate-soybean-corn-basal diet to which either beef tallow or linseed oil or mixture blend of lin-seed oil and beef tallow was included at level of 3 and 4% (starter and finisher, respectively). The mixture blend of tallow and linseed oil achieved better performance and significantly higher body weight than when each fat source was fed solely. Regarding, immune parameters, the linseed oil feeding had significantly improved several immuno indices (haemagglutinin antibody titers against SRBC and delayed hypersensitivity reaction to phytohemagglutinin-P) in broiler chickens over the control and the other fat sources-fed groups. No significant changes were observed due to the inclusion of different fat sources in the relative weights of spleen and thymus, however, the relative weight of the bursa was significantly in creased at age of 3 and 7 weeks in the linseed oil- fed proup. It is to be concluded that whereas linsed oil feeding improved several indices of im muno status in broiler chickens which might be useful to fight infections, it was not able to compete with the tallow-linseed oil mixture in respect to performance. Further studies are needed to evaluate such effects and to understand the mechanism underlying the modulation of the immune system by linseed oil feeding.