Congenital color defectives, who comprise 8% of the male population,1have been studied until recently entirely by psychophysical methods. The object of this paper is to describe the results obtained in the study of color-defective subjects by the method of electroretinography and to compare these results to those obtained by other techniques. These subjects have more than just an interesting novelty but rather an important congenital anomaly, since the severely defective are handicapped in a variety of occupations2as well as in the appreciation of their environment. According to the trichromatic theory of vision there are three color processes.3Protanopes and deuteranopes are both referred to as dichromats, since they require only two color primaries to match all other spectral colors. The protanope is considered partially red-blind, since to him the red end of the spectrum appears darkened. According to most investigators, the deuteranope does not show a loss