We examined the association between aspirin use and the rates of cataract extraction during 8 years of follow-up in a large prospective study of women, the Nurses' Health Study. From 1980 to 1988, we documented 448 senile cataracts diagnosed and extracted during 434,680 person-years of follow-up. While we observed a modest positive association at the higher doses of aspirin use in the age-adjusted analyses, no association was found after accounting for other cataract risk factors (relative risk for > or = 20 years of use, 1.08; 95% confidence interval, 0.84 to 1.39). Among women who consumed seven or more tablets per week for 20 or more years, there was no suggestion of protection; if anything, a nonsignificantly elevated risk was observed (relative risk, 1.31; 95% confidence interval, 0.94 to 1.80). We observed no consistent difference in the relationship between aspirin use and cataract when assessed by age. Overall, we found no evidence to support the substantial reduction in risk of cataract among aspirin users as reported in several previous studies.