Fourteen cases of central retinal vein occlusion (CRVO) were studied with electroretinogram (ERG) and fluorescein angiogram. The cases were divided into a venous stasis retinopathy group (VSR,9 cases) and a hemorrhagic retinopathy group(HR, 5 cases). The b/a ratio and retinal circualtion time (RCT) were measured and compared with the control group. The mean b/a ratio of the HR group (0.86) was decreased as compared with the VSR group (1.18) and the control group (1.23). The RCT of the HR group was markedly delayed to 13.68 seconds as compared with the VSR group (11.09 sec) and the control group (6.4 sec). These facts suggest that both the b/a ratio and the RCT are possible parameters for estimating retinal ischemia and that the ERG is a reliable examination method for classification of CRVO.