OBJECTIVE To evaluate the possible risk factors for posterior chamber intraocular lens dislocation either in-the-bag (ITB) dislocation or out-of-the-bag (OOTB) dislocation. METHODS All subjects who sustained late intraocular lens dislocation from January 2011 until May 2014 and presented to the Nagasaki University Hospital were included in the study. This study is a retrospective evaluation of all cases of posterior chamber intraocular lens dislocation in this defined period. All cases had history of uncomplicated cataract surgery with implantation of posterior chamber intraocular lens. Patients with history of trauma (before cataract surgery) were excluded from the study. The main outcome measures of the study were evaluation of risk factors for dislocation of both groups and determination of the interval between cataract surgery and dislocation. RESULTS Thirty-six eyes (69.23%) suffered ITB dislocation, and 16 eyes (30.77%) suffered OOTB dislocation. Intraocular lens dislocation was common in males (42 eyes = 80.77%) than females (10 eyes = 19.23%). Patients of ITB dislocation group were significantly older than OOTB dislocation group at the time of initial intraocular lens implantation and at the time of exchange surgery. CONCLUSIONS The most prevalent risk factors in both groups were axial myopia in 18 eyes (34.61%), vitreoretinal surgery in 16 eyes (30.77%), and pseudoexfoliation in 13 eyes (25%) in all cases.