Objective To observe the expression of cytochrome C （Cyt C）and apoptosis-related gene Bax in hippocampus of posttraumatic stress disorder（PTSD）rats in order to investigate their effects and relationships. Methods Sixty male Wistar rats were used in the present study. The single-prolonged stress（SPS）-method was carried out to set up the rat PTSD models. There were six groups：after SPS 1，4，7，14，28 days groups and control group. The expression of Cyt C and Bax proteins were detected with immunohistochemistry, double immunofluorescence, confocal laser scanning microscopy and Western blotting. Results The expression of Cyt C peaked at 4 days and maintained higher level at 7 days after SPS. At 7 days after SPS, strong immunoreactivity of Bax was noticed,At 14 days after SPS, the expression of Bax was down-regulated and then gradually decreased. Conclusion Bax is