Authors investigated the effects of intravenous anesthetics(pentothal, thalamonal, valium) on visual evoked potentials with 8 cats. The following results were obtained: 1) Visual evoked potentials was not obtainable with pattern shift visual stimulation. 2) With usual anesthetics, visual evoked potentials showed little change in all drugs. 3) With high dosage of anesthetics, visual evoked potentials revealed marked delay of latency and decrease of voltage in all drngs. 4) Latency was more reliable parameter than voltage in evaluation of visual evoked potential. 5) Effects of thalamonal on latency was more stable than pentothal and thalamonal.