Objective To investigate the effects of simple hypobaric hypoxia on parameters of hematology and blood rheology in order to establish a rat model of simulated high altitude polycythemia(HAPC) for the study of pathophysiologic mechanisms and medical prevention and treatment of HAPC.Methods Fortyeight male Wistar rats were randomly divided into three normal control groups and three hypoxia model groups.Normal control group rats were bred in normoxia conditions,and hypoxia group rats were subjected to hypoxic exposure for 8 hours per day at simulated 5 500 m high altitude in a hypobaric chamber.After hypoxic exposure for 2,4,12 weeks,one group of normal control and hypoxia model rats were killed and blood was collected,respectively.Then parameters of erythrocyte and blood rheology were examined.Results Mucous membrane of hypoxia model rats showed obviously cyanosis after 2 weeks hypoxic exposure.Hemoglobin concentration of hypoxia model rats were beyond 210 g/L after 2 weeks,4 weeks and 12 weeks hypoxia exposure and significantly increased than that of normal control rats respectively.Besides,RBC counts,hematocrit,whole blood viscosity,erythrocyte aggregation index of hypoxia model rats were all notably higher than those of normal control rats respectively.Conclusion A rat model of high altitude polycythemia can be rapidly established by hypobaric hypoxia exposure at simulated 5 500 m high altitude for 8 hours daily. Objective To investigate the effects of simple hypobaric hypoxia on parameters of hematology and blood rheology in order to establish a rat model of simulated high altitude polycythemia (HAPC) for the study of pathophysiologic mechanisms and medical prevention and treatment of HAPC. Methods Fortyeight male Wistar rats were randomly divided into three normal control groups and three hypoxia model groups. Normal control group rats were bred in normoxia conditions, and hypoxia group rats were subjected to hypoxic exposure for 8 hours per day at simulated 5 500 m altitude altitude in a hypobaric chamber. After hypoxic exposure for 2, 4, 12 weeks, one group of normal control and hypoxia model rats were killed and blood was collected, respectively. These parameters of erythrocyte and blood rheology were examined. Results Mucous membrane of hypoxia model rats showed obviously cyanosis after 2 weeks hypoxic exposure. Hemoglobin concentration of hypoxia model rats were beyond 210 g / L after 2 weeks, 4 weeks and 1 2 weeks hypoxia exposure and significantly increased than that of normal control rats respectively.Besides, RBC counts, hematocrit, whole blood viscosity, erythrocyte aggregation index of hypoxia model rats were all notably higher than those of normal control rats respectively. Confluence A rat model of high altitude polycythemia can be rapidly established by hypobaric hypoxia exposure at simulated 5 500 m high altitude for 8 hours daily.