Purpose To assess 3-year incidence and associated factors of posterior capsule opacification (PCO) after phacoemulsification surgery. Design Cohort study. Methods A total of 1934 consecutive patients aged ≥64 years undergoing phacoemulsification surgery at Westmead Hospital were recruited, of whom 1495 (77.3%) had retroillumination anterior segment images taken of the surgical eyes after 1 month and at a further postoperative visit within 3 years. Severe PCO was defined if the view of the optic disc was obscured, or neodymium-yttrium- aluminum-garnet capsulotomy was performed. Cumulative incidence of PCO was estimated using Kaplan-Meier methods. Associations of PCO with surgeon groups and different types of implanted intraocular lenses (IOLs) were assessed, adjusting for age, sex, diabetes, and ethnicity. Results Three-year cumulative incidence of PCO was 38.5% (95% confidence interval [CI] 36.1%-40.9%) among the 1495 patients, including 4.7% (95% CI 3.5%-5.8%) with severe PCO. PCO incidence was higher in: (1) eyes operated on by junior trainees (49%) compared to those by senior ophthalmologist surgeons (36%) (adjusted odds ratio [OR] 1.6, 95% CI 1.2-2.0); and (2) eyes with hydrophobic, 3-piece (either square-edged [51%, OR 2.3, 95% CI 1.4-3.6] or partial-round-edged [39%, OR 1.5, 95% CI 1.1-2.1]), or hydrophilic IOLs (64%, OR 2.9, 95% CI 1.9-4.4) compared to those with single-piece, square-edged, hydrophobic IOLs (34%), after additional adjustment for surgeon group. Conclusions Predominantly mild PCO occurred in one-third of eyes after phacoemulsification surgery. Possible predisposing factors associated with PCO development include surgery performed by ophthalmologic trainees and the use of hydrophilic or other hydrophobic IOLs apart from the single-piece, square-edged one.