The contamination of animal feed with mycotoxigenic fungi is a disastrous problem along the food chain. Pichia anomala and Schwanniomyces occidentalis were applied as a biocontrol yeast to prevent Aspergillus flavus growth in vitro and in feed corn. The yeast strainswere able to inhibit mycotoxigenic fungi growth on animal feeds and improve the properties of the feed.The enzymes assay indicated that P. anomala was able to produce β-1,3-glucanase and chitinase which could propose a mode of action for its antifungal activity. Scanning electron micrographs of fungal hypha cultures with P. anomala revealed that yeast cell could colonize the fungal hypha leading to their lysis and deterioration. Schwanniomyces occidentalisproduces enzymes, including a-amylase and glucoamylase,and excretes very efficiently large protein (glucoamylase).The experimental treatments T with rats divided as follows: T1 was fed as basal diet (control), T2 the contaminated diet with aflatoxins (AF) at3ml suspension of fungi/1kg diet from T3:T8wheredifferent concentrations of yeasts were added.T9was similarto T4 without AF and T10 was similar to T6 without AF. The results showed that T2caused significantly lower final body weight and total body weight gain and significantly higher mortality rate, kidney functions(creatinineand urea) and liverfunctions (AST, ALT and ALP) ,beside histopathologicaleffects in Liver, Kidney and spleenthat,Vaculation ofepithelial lining renal tubules, hydropic degemenration of hepatocytes and hemorrhage.On the other hand, the treatmentsT3-T8had significantly an improvement in performance as compared with T2 whichshowedsignificantly higherfinally body weight  p˂ 0.02% and total body weight gain and lower mortality rate, Kidneyfunctions(CREATININE and Urea) and liverfunctions (AST, ALT and ALP),histopathological examination of  in Liver tissue shows activation of Kupffer cells and nohistopathological changes in Kidney and spleen. The results showed the ability of one of yeasts(P. anomala or Schwan.occidentalis)or theirmixture for inhibiting mold growth andit's toxigenic effects.