To examine the possible predisposing factors for intraocular lens (IOL) dislocation within the capsular bag (in-the-bag dislocation) and IOL dislocation outside of the capsule (out-of-the-bag dislocation) and to study surgical outcomes of explantation of dislocated IOLs and scleral suturing of posterior chamber IOLs. Retrospective interventional case series. Thirty-eight eyes of 38 patients who developed in-the-bag IOL dislocation and 24 eyes of 24 patients who experienced out-of-the-bag dislocation. Medical records of 62 consecutive patients who underwent IOL exchange surgery for dislocation between 1999 and 2005 were reviewed. Possible predisposing factors and the other characteristics of in-the-bag and out-of-the-bag IOL dislocations; outcomes of IOL exchange surgery, including visual acuity (VA) and refractive status before and at 12 months after surgery; and serious postoperative complications. Possible major predisposing factors for in-the-bag IOL dislocation were pseudoexfoliation (17/38 [44.7%]), retinitis pigmentosa (4/38 [10.5%]), the status after vitrectomy (2/38 [5.3%]), trauma (2/38 [5.3%]), and a long axis (2/38 [5.3%]), whereas those for out-of-the-bag dislocation were secondary IOL implantation (11/24 [45.8%]), surgical complications (3/24 [12.5%]), mature cataract (3/24 [12.5%]), and pseudoexfoliation (2/24 [8.3%]). The interval between IOL implantation and exchange surgery was significantly shorter for the in-the-bag dislocation group than for the out-of-the-bag dislocation group (P = 0.0006). Mean uncorrected VA improved significantly after IOL exchange (P = 0.0080), and corrected VA also tended to improve, although the improvement was not significant (P = 0.0704). Mean absolute value of spherical power decreased significantly after surgery (P = 0.0008), whereas refractive astigmatism showed a significant increase (P = 0.0003). The primary serious complications after surgery were a marked rise in intraocular pressure (12/62, 19.4%), retinal detachment (4/62, 6.5%), and redislocation (2/62, 3.2%). Possible major predisposing factors for in-the-bag IOL dislocation are pseudoexfoliation, retinitis pigmentosa, the status after vitrectomy, and trauma, whereas those for out-of-the-bag dislocation are secondary implantation, surgical complications, and mature cataract. After IOL exchange surgery, corrected VA does not improve markedly. Because the incidence of postoperative complications after IOL exchange with scleral suturing is high, the use of other surgical techniques should be considered.