Purpose: Senile cataract contributes to 75% of blindness in India and there is a growing backlog of cataract cases needing surgery. The present study seeks clues to the etiology of senile cataract, so that strategies to prevent or even delay cataract formation could be planned. Methods: Using a community based case-control design, 258 cases & 308 controls from one centre and 301 cases & 591 controls from another were studied. The subjects were from rural areas and were aged 40-60 years. Logistic regression analysis technique was employed to study the associations between senile cataract and various variables. Results: Systolic blood pressure, duration of exposure to sunlight per day were associated with senile cataract in both the centres (OR=1.4 & 1.5 for sysstolic BP and 1.6 & 1.4 for exposure to sunlight). Utilization of rice gruel (OR=0.5), duration of exposure to fire & dust per day (OR=1.8), family history of cataract (OR=5.0), use of cheap cooking fuels (OR=1.8), increased height (OR = 0.7) and increased number of hours of work per day (OR=0.7) were other variables that showed significant association in either of the centres. Conclusions: Senile cataract appears to have a multi factorial etiology. Though the study provided some clues to the etiology of senile cataract, further studies are needed to know the specific role of these factors in the causation of cataract, so that any preventive or control measures could be initiated in the community. Till such time, we have to fall back on the available surgical approach in control of senile cataract. J Epidemiol, 1999; 9 : 327-336