A prospective in vivo study of 50 intraocular lenses was done to document the long-term results and biocompatibility of heparin-surface-modified poly(methyl methacrylate) posterior chamber lenses. Continuous curvilinear capsulorhexis and phacoemulsification were performed throughout and examinations were by slit-lamp and specular microscopy. Decentrations of more than 1 mm were seen in 4% of eyes. Stress folds from the haptic traction forces were detected in 16%. A posterior capsulotomy was performed in 10% because of fibrosis or Elschnig pearl formation. Fine fibers were found on the lens surface in 76%. During the first postoperative days only a moderate number of fibroblast-like cells was observed. Foreign-body giant cells were seen in 8%. All cases with foreign-body giant cells had posterior synechias. Visual performance and clinical results were comparable to those of other well-approved intraocular lenses. The low percentage of cellular reaction on the lens surface suggests good biocompatibility.