Objective:To explore the expression and distribution of heme oxygenase isoforms(HO-1 and HO-2) in liver and spleen of cirrhotic rats. Methods:Liver cirrhosis was induced by the subcutaneous administration of CCL4. Distributions of HO-1 and HO-2 in rat tissues were examined immunohistochemically using polyclonalantibodies. The pathologic changes and expression of HO-1 and HO-2 in rat tissues were observed by light microscope and compared using image analysis system. Results:Compared with the controls, HO-1 positive cells were more abundant and intensive in liver and spleen of cirrhotic rats and mainly located in portal areas of liver and in red pulp of spleen. However, no statistical difference of HO-2 between cirrhotic rats and controls was observed. Conclusion:The HO-CO pathway may be involved in the development of liver cirrhosis and pathogenesis of the portal hypertension.