Abstract: In the present study pure strains of Bacillus subtilis, B. pumilus and B. sphaericus were used to antagonized indigenous fungi of cassava products with the aim of evaluating their potentials in reducing the toxicological and pathological consequences associated with the indigenous fungi. The protective effect was studied using rat bioassay. Toxicological data of rat plasma showed that Bacillus species had liver improvement functions. There was a significant (p = 0.05) decrease in the plasma aspartate aminotransferase of treated rats indicating no possible damage to the liver (hepatotoxic), while there was non significant (p = 0.05) rise in the plasma protein. Moreover, the administration of Bacillus sp. had no negative haematological (packed cell volume, haemoglobin count and white blood cell counts) effect. Further pathological investigation revealed that the kidney and pancreas were protected by the administration of the organism.