Posterior capsule opacification (PCO) is one of the most common complications of phacoemulsification with intraocular lens (IOL) implantation. This retrospective study evaluated the incidence of neodymium: YAG (Nd:YAG) laser capsulotomies for PCO in two groups of patients with different sizes of poly(methyl methacrylate) (PMMA), capsular bag-fixated IOLs. We evaluated 437 eyes that had phacoemulsification with continuous curvilinear capsulorhexis over a four-year period. Patients were placed in one of two groups, based on IOL size: large IOL (lens length 13.5 mm or greater) and small IOL (lens length less than 13.5 mm). In the large IOL group, 106 of 280 patients (38%) required YAG laser posterior capsulotomy; in the small IOL group, 25 of 157 patients (16%) did. This difference was statistically significant even though the average follow-up was 84.1 weeks in the large IOL group and 54.1 weeks in the small IOL group.