Abstract: Objective To study the changes of heat shock protein 70 (HSP70) in the brain of rabbits with craniocerebral missile injury (CMI) and their impact on the injury in a hot and humid environment (HHE). Methods Twenty-four New Zealand white rabbits were randomized into 3 equal groups, namely normal temperature (NT) control group (subjected to treatment at temperature of 22.0±0.5 ℃ with relative humidity of 50%), NT gunshot group with CMI and HHE gunshot group with CMI. The rabbits in the latter two groups were subjected to normal temperature of 22.0±0.5 ℃ with relative humidity of 50% and environmental temperature of 39.0±0.5 ℃ with relative humidity of 80% to 85%, respectively, after establishment of CMI models. HSP70 in the brain tissues and lymphocytes was detected by Western blotting and visualized using chemo- luminescence and X-ray films, followed by quantitative gel image analysis. Results Expressions of HSP70 in the cortex, hypothalamus and lymphocytes increased apparently in HHE gunshot group, and the changes of HSP70 in the lymphocytes were consistent with those in the cerebral cortex and hypothalamus. Conclusion HSP70 expression in the brain tissues and the lymphocytes increase evidently after MCI in HHE.