Fifty animals, cattle and buffaloes (25 each) aged from 5-7 years old were selected randamly. They were raised at governmental project and slaughtered in Bani Adi and Elhawatka slaughter houses (Assiut, Egypt). Random samples of feed stuff and water (10 for each) were taken from the farm were the animals raised on. Haemogram showed that cattle and buffaloes suffering from cobalt deficiency had significantly decreased values of RBCs, PCV, Hb, MCV, MCH, MCHC and WBCs. According to serum biochemistry: cattle and buffaloes had lower levels of cobalt, significantly lower values of total proteins, albumin, and globulin. more over the activities of AST and ALT and the concentrations of blood urea nitrogen showing a marked increase in the animals suffered from lower cobalt levels. According to the histopathological findings: Livers of Co-deficiency animals were exhibited varying degrees of vacuolar degeneration and necrotic changes with cytoplasmolysis and karyorhxis of the hepatic nucleus reached to its lyses. Diffuse fatty changes were also observed. The central veins were congested and surrounded with degenerated hepatocytes and increased number of kupffer cells some cases showed portal cirrhosis with lymphocytic infiltration. The kidneys showed sever degenerative changes in the renal tubules including cytoplasmolysis in the cytoplasm and lyses of the nucleus, congestion of the glomeruli were also observed. Therefore we should follow up cobalt levels in our farm animals to prevent its deficiency in our farms to prevent its deficiency in our farms in Assiut Governorate.