This paper reports a series of biological effects induced by chronic γ-irradiation combined with benzene injection in rabbits. 30 healthy male rabbits, 6-7 months of age, were equally divided into 6 groups 5 in each one. Animals of control and radiation, low benzene and low benzene radiation, high benzene and high benzene radiation groups were injected subscutaneousl with 0.6 ml peanut oil, 0.6 ml peanut oil 0.06 ml benzene or 0.6 ml peanut oil + 0.6 ml benzene/d/rabbit, respectively, 5 days per week for 14 weeks. After injection, animals of radiation, low benzeae radiation, high benzene radiation groups were irradiated at 0.899 mGy/min. × 60/d. The main results were summarized as follows: (1) The changes of hematopoietic function are close related to the injected dosage of benzene. Damages of hematoietic function in rabbits are enhanced by combined effect of benzene and γ-rays. (2) γ-rays and benzene can induce chromosome aberrations and SCEs. Chromosome aberrations in blood lymphocytes are higher than in marrow cells. Chromosome aberrations induced by γ-rays are higher than SCEs, but no significant linear correlation between the dosage and effects was found. The SCEs of blood lymphocytes induced by benzene are more obvious than chromosome aberrations, moreover, linear dose effect correlation of acentrics in high benzene group and SCE in high benzene and low benzene radiation grous were observed. The chromosome aberration yield induced by γ-rays can signifieantly be enhanced by treatment with benzene. The combined cytogenetic effects of radiation with benzene could be synergetic mainly in dicentrics plus rings,being mainly additive in acentrics. SCEs induced by benzene combined with γ-radiation could be enhanced in the low benzene radiation group. (3) Benzene is a weak mutagen for male reproductive cells, because it can induce more abnorml sperms. Histological damages of testes in rabbits were also enhanced by combined effect of γ-radiation and benzene.