To investigate the contribution of endothelial dystrophy to the subsequent development of pseudophakic bullous keratopathy, we retrospectively reviewed the clinical records and histopathologic specimens of pseudophakic patients who had undergone penetrating keratoplasty for corneal decompensation. Conclusive evidence of endothelial dystrophy was found in a majority (18 of 27, 67%) of patients who developed pseudophakic bullous keratopathy following implantation of a posterior chamber intraocular lens. By contrast, the incidence in a comparable group of 51 pseudophakic bullous keratopathy patients with anterior chamber intraocular lenses was low (six of 51, 12%) (P less than 0.01). In analyzing the relative risk of post-surgical corneal decompensation, one cannot implicate a particular intraocular lens without considering pre-existing endothelial dystrophy.