Electroretinographic studies were conducted on 19 Aotus monkeys. Seventeen of the animals were anesthetized with pentobarbital sodium, and two were quieted with Flaxedil and used unanesthetized. Studies of the response of the dark-adapted and light-adapted eye to flashes of light failed to reveal either a Purkinje shift or a photopic luminosity function. Studies on 12 animals using flicker techniques revealed a Purkinje shift in 9 animals and a typical photopic luminosity function in 6 animals. Three animals displayed no shift at all. In all cases, response magnitude by intensity curves were constructed and equal response curves determined. Equal response curves for brief flashes of light and 4-cycles/sec flicker closely parallel the ICI (International Commission on Illumination) scotopic function, and equal response curves for 12- and 20-cycles/sec flicker in six animals are in fair agreement with the ICI photopic function. Three animals produced bimodal curves with maxima at 510 and 590 µ.