This study was investigation effect of Cobalt radiation on liver of Wistar rats. The results showed that the use of different levels of dosage dependent changes in different parts of the liver tissue. On the first day after the irradiation the animals were very lethargic. Areas of necrotic hepatocytes and cell swelling were seen in G3 and G4. But in the group 4 severe congestion was seen. Also pathological study of spleen was showed that necrosis in some parts of the spleen in 3 exposed groups and fibrinoid degeneration in the central splenic vein in group 4.
