Of 226 patients who had an intraocular lens implanted over a three year period, 6.2% developed bullous keratopathy compared with 2.2% of 90 patients who had a standard cataract extraction performed by the same surgeon. An additional 4.0% of the lens implant patients developed peripheral or intermittent corneal edema. The factors related to the higher incidence of this complication in lens implant patients included corneal touch during implantation, prolonged postoperative iritis and, in cases of mild or peripheral corneal edema without bullous keratopathy, recurrent lens dislocation. The most consistent pathologic findings in 10 corneas that required keratoplasty were epithelial edema and loss of corneal endothelium. Means to prevent this complication are discussed.