The objective of this research was to determine the effect saccharomyces enriched with selenium yeast (SeY) on Rahmani sheep and to evaluate the influence of the oral supplementation of saccharomyces enriched selenium on growth performance, Haematobiochemical, and antioxidant parameters in such sheep. Twenty Rahmani  sheep were allocated into 4 groups ,  each group have five sheep, which were control group : received basal diet and not exposed to heat stress, Heat stress group (HS): received basal diet and exposed to heat stress, heat stressed with Saccharomyces enriched selenium(HS+SeY):received basal diet containing Saccharomyces enriched selenium and exposed to heat stress, non-heat stressed group with Saccharomyces enriched selenium (NHS+SeY):received basal diet with Saccharomyces enriched selenium and not exposed to heat stress. Temperature and humidity index were calculated. Experiment undergoes for two months (July and August). The results showed that Saccharomyces enriched selenium causes significant improvement in feed efficiency in sheep under heat stress. Saccharomyces enriched selenium supplementation to Hs sheep showed improvement of Haematological indicator and tendency toward normal values indicating positive effect of Saccharomyces enriched selenium. Furthermore, the findings of the study demonstrated that selenium enriched saccharomyces diet have positive impact on various blood metabolites, such as glucose, total protein, albumin, globulin, liver and kidney enzymes, and triglyceride levels in heat stressed sheep. Feeding Saccharomyces enriched selenium under heat stress to sheep not only cause significant decrease in serum malonaldehyde (MDA) concentration as indicator of lipid peroxidation, but also cause significant increase in glutathione peroxidase (GPx), catalyse (CAT) and superoxide dismutase (SOD) activity. In summary, inclusion of Saccharomyces enriched selenium to  sheep diet during summer condition, is advantageous to growth performance, haematobiochemical and antioxidant parameters of Rahmani sheep.