Intraocular lenses removed because of recurrent episodes of intraocular inflammation showed bacteria adhering to the prosthesis. Infections localized to areas around intraocular lenses have been reported in the literature. Two such infections and an in vitro study of bacterial adherence to implant surfaces are reported. Adherent bacteria were found to be more numerous on the polypropylene haptic than on the polymethylmethacrylate optic in both in vitro and in vivo cases. We suggest that the intraocular lens becomes contaminated with commensal organisms of low virulence during insertion into the eye, and that these organisms are the source of the inflammatory episodes. Experiments show that lenses as supplied are sterile and that in vitro bacteria adhere preferentially to the haptic.