Visual functions including color vision and spectral sensitivity were investigated in 18 of 36 patients and in 2 persons with normal visual acuity in 8 families with dominantly inherited juvenile optic atrophy. Seven of the 8 families had at least one member who showed mainly acquired blue-yellow color vision deficiency. However, only 4 patients showed typical blue-yellow color vision deficiency, which suggested nonspecific characteristics of color vision deficiency in optic neural diseases. One family showed mainly acquired red-green color vision deficiency. Spectral sensitivity functions measured in 5 patients of 3 families showed sensitivity loss in the middle and long wavelength range as well as markedly decreased sensitivity in the short wavelength range. Decrease in spectral sensitivity in the short wavelength range or minimal blue-yellow color vision defect in a subject's brothers with normal visual acuity is interesting, but further study is needed because blue sensitivity decreases easily in various conditions.