This paper describes a new technique for detecting color-defective individuals, based upon the isolation of a pattern response from the visual evoked response. Specifically designed targets were produced from equal-luminance hues that lie on the confusion lines of deuteranopes, protanopes, and tritanopes. Sixteen color normals, eight deuteranopes, eight protanopes, and one tritanope were tested with these targets. The results showed that color normals give a pattern response to patterns formed of hue differences only; this response is similar to that produced by luminance differences. Color-defective individuals, on the other hand, give no pattern response to targets formed of hues that they cannot discriminate, although they give pattern responses for luminance differences.