Leisure time sunlight exposure is a small or insignificant portion of total sunlight exposure experienced by most people at high risk for cataract. Few studies have been undertaken to evaluate a possible causal relationship, and these have largely been in Western countries. Analyses of data from the National Health and Nutrition Examination Survey (1971-1972) failed to confirm a relationship between leisure time exposure and cataract, but suggested that total exposure to sunlight was significantly related to cataract. A case-control study of cataract in Iowa suggested that controls were more likely to have shielded their eyes from sunlight than cases. A study in Italy suggested a positive relationship between leisure time sunlight exposure and lens opacities. In the large population-based Beaver Dam Eye Study population, we evaluated estimates of sunlight exposure and cataracts. We did not find that more leisure time sunlight exposure was associated with lens opacities. However, in men, estimates of lifetime exposure to ultraviolet-B were associated with cortical cataract. In summary, there is evidence to suggest that sunlight exposure may be related to cataract in diverse populations. Leisure time sunlight exposure is probably responsible for a small portion of that exposure.