Purpose: To study the characteristics of PEDF in cataractous aqueous humor and its expression in human lens epithelium. Methods: The PEDF concentration in the aqueous humor was measured by enzyme -linked immunosorbent assay in senile (130cases) and congenital (18cases) cataract patients who underwent cataract phacoemulsification extraction surgery. Anterior lens capsular specimens were obtained from these patients to count lens epithelial cells (LEC) density. The Lens Opacities Classification System Ⅲ was used to classify the senile cataracts as cortical, nuclear, posterior subcapsular and mixed types of opacity, and quantitative analysis of the nuclear opacities was performed by Pentacam Scheimpflug imaging system. Anterior lens capsular specimens from another senile (10cases) and congenital (10cases) cataract were collected for immunofluorescence with polyclonal antibodies specific to human pigment epithelium -derived factor (PEDF). Results:The mean aqueous level of PEDF was(178. 9±87. 5)ng/ml, and there was negative linear correlation of PEDF level and age (r=0. 811, P<0. 001). In senile cases, the aqueous PEDF concentration decreased with increasing nuclear opacities (r=0. 447, P < 0.01) , and the mean PEDF level in nuclear cataract was significantly lower than that in posterior subcapsular opacity (P < 0.01) . PEDF immunostaining was detected in LEC of all capsular specimens. Conclusion : The PEDF level in human aqueous humor is related to age, types of cataracts and lens opacity. PEDF also express in human LEC. The study results suggest PEDF may regulate and/or protect LEC by paracrine and autocrine, and lack of PEDF may play a role in cataractogenesis. Purpose: To study the characteristics of PEDF in cataractous aqueous humor and its expression in human lens epithelium. Methods: The PEDF concentration in the aqueous humor was measured by enzyme-linked immunosorbent assay in senile (130cases) and congenital (18cases) cataract patients who The lens Opacities Classification System III was used to classify the senile cataracts as cortical, nuclear, posterior subcapsular and mixed types of opacity , and quantitative analysis of the nuclear opacities was performed by Pentacam Scheimpflug imaging system. Anterior lens capsular specimens from another senile (10cases) and congenital (10cases) cataract were collected for immunofluorescence with polyclonal antibodies specific to human pigment epithelium -derived factor (PEDF) Results: The mean aqueous level of PEDF was (178. 9 ± 87. 5) ng / ml, and there was negative linear correlation of PEDF level and age (r = 0. 811, P <0. 001). In senile cases, the aqueous PEDF concentration decreased with increasing nuclear opacities (r = 0. 447, P <0.01), and the mean PEDF level in nuclear cataract was significantly lower than that in posterior subcapsular opacity (P <0.01). PEDF immunostaining was detected in LEC of all capsular specimens. Conclusion: The PEDF level in human PEDF also express in human LEC. The study results suggest PEDF may regulate and / or protect LEC by paracrine and autocrine, and lack of PEDF may play a role in cataractogenesis.