A family is described with 20 members in three successive generations affected by optic atrophy without other ocular or extraocular manifestations. The anomaly was transmitted as an autosomal-dominant character. There was a clearly bimodal distribution of severity: 4 male patients complained of severe impairment of vision since childhood while 16 other subjects (7 males and 9 females) were completely asymptomatic. This family could be an example of a new variety of autosomal dominant optic atrophy characterized by sex-influenced severity.