We conducted a population-based survey in the Hamar tribe of Ethiopia to assess the problem of blindness and ocular morbidity. Blindness was detected in 1.9% of the Hamar. Among the age group 40 and over < 1.0% of men and 13% of women were blind. Women with low vision or blindness comprised 30% of all women while men with low vision or blindness only comprised 8% of men in the age stratum. Cataract is responsible for the excess blindness in women. Even mild visual disability is less common in men. In Hamar society men have two roles: as herders and as warriors. Warriors with visual loss will be less successful in defending themselves. We suggest that Hamar men who develop visual loss have increased mortality compared to women with visual loss. Vision loss in women does not appear to have life-threatening consequences. Cessation of hostilities between the Hamar and their neighbours could, conceivably, lead to an 'increase' in the incidence of vision loss among men.