the experimental animals is important materials and methods in life science research.. Almost all of drugs used in humanbeing are produced based on test in experimental animals. Various kinds of animal models are needed in the research fields of radiobiology, oncology and immunology, etc. Through hybridization between compatriot brother and sister for 20 generations continuously, we breed successfully IRM 2 inbred mouse whose paternal strain is 615 inbred mouse and maternal strain is ICR/JCL mouse. IRM 2 mouse, produced 52 generations, is characteristic of prolific and fast upgrowth. IRM 2 mice are suitable for the models of acute radiation damage, spontaneous tumor and transplanting tumor. To conforming the genetic homozygosity and quality of IRM 2 mouse, we performed skin grafting test, coat color test and biochemical marker analysis. Moreover, we established RAPD fingerprinting of IRM 2 mouse, showing the genetic character of the mouse. All results of these tests demonstrated that IRM 2 inbred strain mouse is high homogenous in the genetic characteristics. We clarified the G band pattern and spontaneous aberration frequencies of IRM 2 mouse because these are important for drugs screening, radiation effect, cancer research and gene map. Some discerned points between similar banding of chromosomes were presented. The results of aberration analysis showed that break was 0.33%, acentric aberration and translocation were 0.08%. The spontaneous aberration frequencies were very low. Parameters of Organ weight, hematology and biochemistry which are very important characteristics of experimental animals are both frequently used data in experimental and required item of chronicity toxicity test. 13 serum biochemistry parameters were measured using semi auto chemistry analyzer. The peripheral blood cell count and leucocyte differential count were analyzed and the myelogram was examined on regular method. The results of these parameters are relatively stable and less difference among individual. To determine the resistance of the IRM 2 inbred strain mouse to ionizing radiation, examinations for the changes of nucleated cell count in bone marrow, DNA content of bone marrow cells, WBC in peripheral blood and CFU S were performed in IRM 2 mouse following irradiated with 4.0 Gy of 137 Cs γ rays. A declining degree of WBC, the nucleated cell count and DNA content in IRM 2 mouse after irradiating was lower but recovery was quicker than in both ICR and 615 mouse, CFU S in IRM 2 was 2 times higher than in both ICR and 615. LD50 of IRM 2 mouse toγ rays were 7.17(♂)- 7.50(♀)Gy, that is, 1.73-1.57Gy and 1.44Gy higher than those of ICR and 615(P<0.01), respectively. IRM 2 mouse possessed higher resistance to ionizing radiation than other inbred and outbred strain mouse. To establish Spontaneous and transplanting tumor model in the Radiation resistant IRM 2 inbred mouse, we performed experiments as follows: (1)The Spontaneous lymphoma tissue from IRM 2 mouse were cut into several fragments sized 2.0 mm 3 then implanted subcutaneously one IRM 2 mouse, (2) breast cancer tissues from Jin BaiⅡ mouse and T 739 lung adenocarcinoma tissues were pounded and suspended in physiological saline, cell suspension were of 0.2ml (1 ×10 6cells ) injected subcutaneously into IRM 2 mouse. The frequency of tumorigenesis and survival day of bearing tumor animal were examined. The spontaneous malignant lymphoma were implanted 70 times, using 968 mice, the T 739 lung adenocarcinom were implanted 45 times .using245 mice, the breast cancer were implanted 5 times ,using 50 mice, The frequencies of tumorigenesis were 100 % for all three types of tumor, The average survival day of animal bearing lymphoma ,T 739 lung adenocarcinoma, and breast cancer were 26.0±1.6, 21.1±1.9 and 25.5± 2.8d, respectively. The results shown that tumor models established in IRM 2 inbred mouse are steady. the experimental animals is important materials and methods in life science research .. Almost all of drugs used in humanbeing are produced based on test in experimental animals. Various kinds of animal models are needed in the research fields of radiobiology, oncology and immunology, etc. Through hybridization between compatriot brother and sister for 20 generations continuously, we breed successfully IRM 2 inbred mouse whose paternal strain is 615 inbred mouse and maternal strain is ICR / JCL mouse. IRM 2 mouse, produced 52 generations, is characteristic of prolific and fast upgrowth . IRM 2 mice are suitable for the models of acute radiation damage, spontaneous tumor and transplanting tumor. To conform to the genetic homozygosity and quality of IRM 2 mouse, we performed skin grafting test, coat color test and biochemical marker analysis. RAPD fingerprinting of IRM 2 mouse, showing the genetic character of the mouse. All results of these tests demonstrated that IRM 2 inbred strain mouse is high homogenous in the genetic characteristics. We clarified the G band pattern and spontaneous aberration frequencies of IRM 2 mouse because these are important for drugs screening, radiation effect, cancer research and gene map. banding of chromosomes were presented. The results of aberration analysis showed that break was 0.33%, acentric aberration and translocation were 0.08%. Parameters of Organ weight, hematology and biochemistry which are very important characteristics of experimental animals are both used data in experimental and required item of chronic toxicity test. 13 serum biochemistry parameters were measured using semi auto chemistry analyzer. The peripheral blood cell count and leucocyte differential count were analyzed and the myelogram was examined on regular method. The results of these parameters are relatively stable andless difference among individuals. To determine the resistance of the IRM 2 inbred strain mouse to ionizing radiation, examinations for the changes of nucleated cell count in bone marrow, DNA content of bone marrow cells, WBC in peripheral blood and CFU S were performed in IRM 2 mouse following irradiated with 4.0 Gy of 137 Cs γ rays. A declining degree of WBC, the nucleated cell count and DNA content in IRM 2 mouse after irradiating was lower but recovery was quicker than in both ICR and 615 mouse, CFU S in IRM 2 was 2 times higher than both ICR and 615. LD50 of IRM 2 mouse to γ ​​rays were 7.17 (♂) - 7.50 (♀) Gy, that is, 1.73-1.57Gy and 1.44Gy higher than those of ICR and 615 (P <0.01), respectively. IRM 2 mouse possessed higher resistance to ionizing radiation than other inbred and outbred strain mice. To establish Spontaneous and transplanting tumor model in the Radiation resistant IRM 2 inbred mouse, we performed experiments as follows: (1) The Spontane ous lymphoma tissue from IRM 2 mouse were cut into several fragments sized 2.0 mm 3 then implanted subcutaneously one IRM 2 mouse, (2) breast cancer tissues from Jin Bai Ⅱ mouse and T 739 lung adenocarcinoma tissues were pounded and suspended in physiological saline, cell suspension The frequency of tumorigenesis and survival day of bearing tumor animal were examined. The spontaneous malignant lymphoma were implanted 70 times, using 968 mice, the T 739 lung adenocarcinom were implanted 45 times. using 245 mice, the breast cancer were implanted 5 times, using 50 mice, The frequencies of tumorigenesis were 100% for all three types of tumor, The average survival day of animal bearing lymphoma, T 739 lung adenocarcinoma, and breast cancer were 26.0 ± 1.6, 21.1 ± 1.9 and 25.5 ± 2.8d, respectively. The results shown that tumor models established in IRM 2 inbred mouse are steady.