OBJECTIVE: To investigate the association between metabolic syndrome and some of its components with the incidence of cataract extraction. DESIGN: Population-based prospective cohort study. PARTICIPANTS: A total of 35,369 women, participating in the Swedish Mammography Cohort, aged 49 to 83 years, who completed a self-administered questionnaire about anthropometric measurements and lifestyle factors in 1997. METHODS: The women were followed from September of 1997 to October of 2005. The cohort was matched with registers of cataract extraction in the study area. MAIN OUTCOME MEASURES: Incident surgical extraction of age-related cataract. RESULTS: We identified 4508 incident cases of cataract extractions during 98 months of follow-up. In multivariate analysis, women with a waist circumference >or=80 cm had an 8% increased risk of cataract extraction (rate ratio [RR], 1.08; 95% confidence interval [CI], 0.99-1.17). Women with diabetes had a 43% increased risk of cataract extraction (RR, 1.43; 95% CI, 1.10-1.86), and hypertension was associated with a 12% increased risk (RR, 1.12; 95% CI, 0.99-1.26). Women with all 3 components of the metabolic syndrome (waist >or=80 cm, diabetes, and hypertension) had a 68% increased risk of cataract extraction (RR, 1.68; 95% CI, 1.40-2.02) compared with women without any of these components. Among women aged less than 65 years at baseline with all 3 components of metabolic syndrome, the risk of cataract extraction was approximately 3-fold more (RR, 2.80; CI, 1.94-4.03). CONCLUSIONS: Metabolic syndrome and its components, abdominal adiposity, diabetes, and hypertension, seem to be associated with an increased risk for cataract extraction, especially among women aged less than 65 years.