A total of 104 eyes and 43 resected corneal discs from patients with failed intraocular lens implants (IOL) received over a period of 35 years were subjected to histopathological analysis. Eyes collected at necropsy from 18 people with clinically successful implants were also examined. Corneal decompensation leading to bullous keratopathy was the most frequent reason for failure, followed by glaucoma and intraocular inflammation. Of 18 cases in which inflammation was the principal clinical cause of failure 12 presented as infectious endophthalmitis, but minor degrees of sterile uveitis were fairly common. Retinal detachment was seen in seven cases. The interval between IOL implantation and the onset of serious complications varied from one month to 29 years, indicating that the presence of prosthesis will always entail a latent risk of an adverse tissue response, albeit slight.