Phenylhydrazine (PHZ), a potent chemical causes toxicity on various tissues at various levels. Administration of phenylhydrazine mainly causes haematotoxicity which leads to the haemolytic anemia. In mammals PHZ induced anemia increased the iron absorption in spleen, liver and duodenum and finally iron metabolism was altered. Local demand and supply of Fe would increase erythropoeitic activity of the spleen so the size of spleen was increased that create the splenomegaly. PHZ induced anemia activate immune response which triggers phagocytosis in the spleen and liver. Apart from this administration of PHZ interfere the binding of erythropoietin (EPO) with erythropoietin receptors (EPOR) so that JAK-STAT would be affected.PHZ also showed genotoxic effect by creating single strand DNA damage.