Color blindness developed in five patients apparently because of lesions in the posterior portions of both cerebral hemispheres. Three of them also had symptoms of prosopagnosia. The lesions were neoplastic in two and vascular in three of the patients. It would appear that bilateral, inferior, occipital lobe lesions may be responsible both for acquired cerebral dyschromatopsia and prosopagnosia. Evidence from experimental investigations in primates suggests that the areas of the cerebral hemispheres analogous to those involved in these patients, may be specialized for the processing of colored stimuli.