The prevalence and etiology of visual loss and of eye diseases were determined in the Kingdom of Saudi Arabia. The sample was a stratified geographic cluster sample of 14,577 persons representing the settled population of Saudi Arabia. A nonstatistical sample of 2,233 bedouins was also examined. The survey revealed that 1.5% of the population are blind and another 7.8% are visually impaired according to the World Health Organization definition. The most common causes of blindness include cataract, trachoma, nontrachomatous corneal scars, refractive errors, congenital anomalies, failed medical or surgical treatment, and glaucoma. Refractive errors, amblyopia, and trauma are also important causes of less severe, and often unilateral, lost vision. About 7% of all Saudi Arabians, and 42% of those older than 40 years, have a cataract or its sequelae. Over 3.5% of the population have corneal scars, about half of which are caused by trachoma.