Purpose: To determine the association between hospital and surgeon volume with the incidence of postoperative endophthalmitis. Methods: A prospective cohort study was conducted to analyse the national health insurance claims data of those patients receiving cataract surgery in 2000 in Taiwan. A total of 108 705 patients who received cataract surgery by 1004 surgeons at 494 hospitals were followed to the end of 2002. Stepwise Cox regression was used to analyse the effects of hospital and surgeon volume of cataract surgery on postoperative endophthalmitis after adjustment for patient's age, gender, education, ophthalmic comorbidities, general comorbidities, and surgical factors including operative methods, different types of intraocular lenses, and surgeon's age. Results: The 2-year incidence of postoperative endophthalmitis at high-volume hospitals (0.90%) was lower than low-volume hospitals (1.16%). The incidence of postoperative endophthalmitis by high-volume surgeons (0.59%;) was lower than those by middle-high-volume (0.73%), middle-low-volume (0.80%), or low-volume surgeons (1.16%). After controlling for case mix, the risk of postoperative endophthalmitis of the low-volume hospitals (hazard ratio (HR) = 1.39) was higher than that of the high-volume hospitals. The risk of postoperative endophthalmitis of low-volume surgeons (HR = 1.67) was higher than that of the high-volume surgeons. Conclusions: The provider volume (hospital and surgeon volume) is associated with the risk of postoperative endophthalmitis. The patients who receive cataract surgery at low-volume hospitals or by low-volume surgeons have significantly higher risk of postoperative endophthalmitis than at high-volume hospitals or by high-volume surgeons. Provider volume can be considered in further postoperative endophthalmitis study as a risk factor.