ABSTRACT:OBJECTIVE:To study apoptosis and regeneration of olfactory epithelium cells in mice after radiation injury, and discuss the possible mechanism. METHODS:The animal model of olfactory radiation injury was established by exposure of mice nose to Xray with a dose of 4 Gy. The apoptotic cells and regenerating cells were detected with the method of TdTmediated dUTP nick endlabeling (TUNEL) and the technique of BrdU incorporation and monoclonal antibody labeling respectively. RESULTS:The apoptotic cells of olfactory epithelium increased significantly after radiation, while the regenerating cells increased with less number accordingly. CONCLUTION:Radiation can induce imbalance of apoptosis and regeneration leading to cell loss in olfactory epithelium of mice, which might explain the mechanism of olfactory dysfunction after radiotherapy.