A community-based cross-sectional study on the prevalence and causes of blindness and visual impairment was conducted between July and August 1990 in three rural districts in Ségou region, Mali. The study population consisted of 5871 villagers. In the study area, the overall prevalence of bilateral blindness was 1.7% (standardized rate for age 2.0% +/- 0.4%), of bilateral visual impairment 1.7% (2.1% +/- 0.4%), of unilateral blindness 1.7% (2.2% +/- 0.4%) and of unilateral visual impairment 1.0% (1.2 +/- 0.3%). No important differences were found between districts. Cataract was the most common cause of visual loss (54%) and was most prevalent among those over 50 years of age. In 43%, unilateral blindness was associated with trauma. Other major eye diseases accounting for high percentages of visual impairment were trachoma and glaucoma. Xerophthalmia appeared to be a major public health problem among children in the age group 0-5. It was concluded that blindness is a major public health problem in this region. Some recommendations are given for strengthening integrated primary eye care at the district level in Ségou region.