To develop a method to estimate the cost per quality-adjusted life year (QALY) gained with cataract surgery using large patient registries.Four centers in Sweden. Five hundred patients scheduled for cataract extraction in 1 eye at 1 of 4 centers in Sweden during March 1999 were asked to complete the EQ-5D, a preference-based quality-of-life instrument, and the Catquest, a disease-specific disability measure, before surgery. Multiple regression analysis was used to study the correlation between utility and visual acuity and/or disability and utility and QALY gain through the intervention estimated. Visual acuity and Catquest scores were available for 484 patients. The mean age was 76.1 years; the mean logMAR visual acuity was 0.59 in the surgical eye and 0.26 in the other eye. The mean Catquest disability score was 13.79 and the mean utility, 0.74. Utilities correlated significantly with visual acuity and disability scores, and the correlations remained significant when both were included in a regression model, indicating that the 2 measure different concepts. The hypothetical cost per QALY gained (discounted at 3%) was estimated at 45000 SKr (4500 US dollars) using the Swedish Cataract Registry. The results indicate that visual acuity and visual disability significantly affect utilities controlled for age and ophthalmic comorbidity. It is thus possible to use data on visual acuity and disability in large registries to estimate the cost-effectiveness of cataract surgery and to compare the cost per QALY gained with other health care interventions.