Abstract: Objective To study apoptosis of pulmonary epithelial cells and endothelial cells in mice with pulmonary edema induced by phosgene exposure. Methods Thirty-two mice were divided into normal group and phosgene group with 16 mice in each group. The mice in phosgene group were exposed to phosgene (11.9 mg/L) for 5 min and those in the control group to air. Four hours after exposure, alveolar type Ⅱcells were isolated and cultured to observe their apoptosis by electron microscope and flow cytometry. The lung tissues were also taken for DNA gel electrophoresis and TUNEL assay. Results Apoptotic bodies were observed in alveolar type Ⅱcells under electron microscope in phosgene group, which had higher cell apoptosis rate than the control group [(40.26±7.74)% vs (1.58±1.01)%, P<0.001] as determined by flow cytometry. Ladder-like DNA fragmentation pattern was observed in DNA gel electrophoresis in phosgene group with apoptosis of the pulmonary epithelial and endothelial cells observed by TUNEL. Conclusions Phosgene can induce pulmonary epithelial and endothelial cell apoptosis in mice, suggesting that the mechanism of phosgene-induced pulmonary edema involves apoptosis of the lung cells.