Abstract: Bax, a proapoptotic member of the Bcl-2 family, localizes largely in the cytoplasm but redistributes to mitochondria and undergoes oligomerization to induce the release of apoptogenic factors such as cytochrome c in response to apoptotic stimuli. Cells deficient in Bax are resistant to UV-induced apoptosis. Thus, studying Bax translocation is very important for us to understand the cellular signaling mechanisms mediating UV -induced apoptosis. Most of previous studies on Bax translocation were done by Western blotting or immunoblotting, but these techniques could not monitor the translocation of intracellular Bax in real time. In this study, we monitored the dynamics of Bax translocation during UV-induced apoptosis in single living cell using laser confocal microscope imaging technique. These results demonstrated that Bax translocation was initiated at 5 h ~6 h after UV irradiation, the average duration of this course was 20 min ~30 min.