SEVERE MYELOSUPPRESSION is a common side effect of radiotherapy or chemotherapy. As a mean to stimulate the full-lineage blood cell recovery from severe myeloid suppression, sub lethally irradiated animals were used to evaluate immunological effect of interleukin (IL-12) in bone marrow (BM) transplanted animals. Isologous BM from the same inbred strain, were given to male rats, 1 h post whole body gamma irradiation at a single dose level of 5Gy and subcutaneous injection of 100 ng/ ml IL-12. Irradiation induced a significant drop in haematological values, blood glutathione (GSH) as well as BM viability associated with a significant elevation of serum malondialdehyde (MDA). Related to immunological data, tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) also recorded a significant depression. Irradiated animals receiving BM and IL-12 showed significantly elevated body and spleen weights, erythrocytes count (RBCs), haemoglobin content (Hb) and haematocrit value (Hct%) besides, white blood cells (WBCs) and its differential count, as well as GSH, while MDA was significantly depressed as compared to the irradiated group. BM viability was significantly increased while IL-6 and TNF-α were normalized. The curative action of IL-12 enforcing significant innate response could trigger and augment adaptive immune response by BM transplantation, hence improving oxidative stress. IL-12 administration is proposed as a complementary strategy to treat radiation-induced path-physiology and tripping free radicals accumulations after irradiation.