OBJECTIVE To evaluate the usefulness of the 30-Hz flicker electroretinogram (ERG) in predicting outcome in patients with central retinal vein occlusion using an automated system previously developed to measure parameters of the flicker ERG and using information about the a priori probability of developing neovascularization of the iris in central retinal vein occlusion. METHODS Amplitude and timing were extracted from 30-Hz flicker ERGs of 76 patients with acute central retinal vein occlusion from a previous study. The ability of the ERG to predict the development of neovascularization of the iris based on derived parameters was measured using the area under the receiver operating characteristic curve. RESULTS The predictive ability of the 30-Hz ERG amplitude, as judged by a two-alternative forced-choice procedure, was 92%. The corresponding value for implicit time was 89%. Using Bayes' theorem, we computed the probability of developing neovascularization of the iris based on a single 30-Hz flicker ERG measurement at initial patient presentation. CONCLUSIONS The 30-Hz flicker ERG provides useful information about the patients with central retinal vein occlusion.