Background : Opacity that develops in the crystalline lens of the eye is called the cataract. Decrease amounts of GRP78 involved in the pathogenesis of cataracts by reticulum endoplasmic stress of lens epithelial cells. Aim : The aim of the study was to evaluate the effects of Catechin on sodium-selenite induced cataract formation and activities of GRP78. Methods : 19 µmol/kg of sodium selenite was injection by intraperitoneal to ten day-old Wistar rats. The rats were separated randomly in five groups (n = 5 in each group): a control group, and four cataract induction groups, treated with 0, 50, 100, 200 mg / kg catechin isolates. GMB4 Clone of Green Tea. By slit-lamp bio microscopic we performed degree of lens opacity and analysis of GRP78 by Enzyme-linked immunosorbent assay (ELISA). Results : Both eyes of all rats in Group 1 no cataract formation. 20% of group 2 were found grade 3 cataracts and the remaining four of five (80%) developed grade 4 cataracts. Cataract in the lens of all rats between group 2 and any eyes from groups 3 or 4 and 5 showed a significant difference (P = 0.022, 0.001, 0.001). The degree of cataract formation in groups 3, 4 and 5 decreased. Grp78 levels in Group I, Group III, Group IV and Group V were significantly higher than the mean lens levels in Group II (P <0.01). Conclusion : Reticulum endoplasmic stress in the lens that increased following cataract formation in rats was suppressed by catechin Isolate From GMB4 Clone Green Tea.