PURPOSE: Cataract is considered the main preventable cause of blindness and visual impairment mainly in poor countries. This study was done to evaluate if cataract is still an important cause of blindness in Central-West region of State of São Paulo, Brazil. METHODS: A cross-sectional study was conducted with a systematically randomized sample of households in five cities located in Central-West region of São Paulo State, Brazil. The sample consisted of 4,229 individuals (8,458 eyes) of all ages. All household members were considered eligible. They were submitted to a complete ophthalmological examination (visual acuity with and without visual correction, biomicroscopy, fundoscopy, tonometry, and refractometry). Cataract diagnosis was given to eyes presenting lens opacity in biomicroscopy exam, according to Lens Opacities Classification System II (LOCS II). Eye with a best correction, presenting visual deficiency or blindness caused by cataract was considered after excluded other pathologies that decrease visual acuity (VA). We considered as visual deficiency eyes with 0.05 < VA < or = 0.3 and as blind eyes with VA < 0.05. Visual impairment was considered for individuals with 0.05 < VA < or = 0.3 in the best eye, with the best correction and blindness for individuals with VA < or = 0.05 in the best eye, with the best correction. We considered the number of eyes with cataract, the number of eyes with visual deficiency and blindness and the number of individuals with visual deficiency and blindness. Occurrence frequency was evaluated for eyes separately and together. RESULTS: Cataract frequency in this population was 4.94% (209 individuals), affecting mainly people over 50'ths (92.34%) and females (61.11%). Cataract was the cause of visual impairment for 0.96% and blindness for 0.52% of the total population. CONCLUSION: Our results showed that cataract prevalence in studied region population of the is similar to developed countries.