【Objective】To investigate the possible role of an endoplasmic reticulum stress marker，activating transcription factor 4（ATF4）in the dysfunction and cell apoptosis of trabecular meshwork in vivo，and to provide new clues to investigate the pathogenesis of primary open angle glaucoma（POAG）.【Methods】ATF4 adenoviral vectors or GFP adenoviral vectors as control were injected into the anterior chamber of 6～8 week- old C57BL/6J mice（experimental group：24 mice，24 eyes；control group：23 mice，23 eyes）. Iridocorneal angle tissue was taken at different time intervals after the injection. Frozen sectioning and immunofluorescent staining were performed to detect the fluorescence of the viruses and expression of ATF4 and C/EBP homologous protein（CHOP）. Real time PCR was used to detect the RNA level of the inflammatory factors IL-1α，IL-1β，IL-6 and endothelial leukocyte adhesion molecule-1 （ELAM-1）. TUNEL assay was performed to determine apoptosis of trabecular meshwork cells. Ultrathin sectioning and transmission electronic microscope were used to observe the ultrastructure of the trabecular meshwork cells. Daytime and nocturnal intraocular pressure（IOP） were measured by rebound tonometer 3，7，10，and 13 days after injection. 【Results】GFP fluorescence of adenovirus could be seen in mice trabecular meshwork 24 h after injection in both groups. Markedly increased expression of ATF4 in trabecular meshwork cells could be found in ATF4-injected group 24 h after injection. The RNA level of the inflammatory cytokines was significantly up-regulated in the iridocorneal angle tissues of ATF4-injected eyes compared to the control 3 days after injection. Up-regulated CHOP expression and TUNEL staining， marked distention of rough endoplasmic reticulum were detected in the trabecular meshwork cells of ATF4-injected eyes 7 days after injection. Daytime and nocturnal IOP were elevated in the ATF4-injected eyes 7，10 and 13 days after injection and were significantly different 7 days after injection（P < 0.05）.【Conclusions】Over-expression of ATF4 may lead to up-regulation of inflammatory cytokines and activation of ER stress-associated apoptotic pathway in mice trabecular meshwork tissues. These changes may play an important role in the pathogenesis of increased IOP.