A population-based survey of the prevalence of major blinding disorders was conducted in three villages in central Tanzania. Overall, 1827 people over the age of seven years old were examined. In those age seven and older, the prevalence of bilateral blindness (visual acuity in the better eye of less than 3/60) was 1.26% and monocular blindness (visual acuity of less than 3/60 in one eye) was 4.32% and the prevalence of visual impairment (visual acuity less than 6/18 but greater than or equal to 3/60 in both eyes was 1.04% and in one eye was 1.75%. Corneal opacities were responsible for 44% of bilateral and 39% of monocular blindness and resulted from trachoma, measles often in association with Vitamin A deficiency, keratoconjunctivitis, and the use of traditional eye medicines. Cataracts accounted for 22% of bilateral and 6% of monocular blindness. Readily preventable or reversible causes of blindness were responsible for 65% of cases of bilateral and 46% of monocular blindness.