Posterior chamber intraocular lenses (PC-IOL) were implanted in 42 eyes of 24 severely mentally and physically handicapped patients, and the results were analyzed in comparison with implants in conventional patients. The patient eyes included in this study were 21 eyes of 13 severely mentally retarded patients, 19 eyes of 10 Down's syndrome patients, and 2 eyes of a patient suffering from mitochondrial encephalomyopathy. Surgeries had been performed under general anesthesia and resulted in significant improvement in vision and quality of life. Severe postoperative complications occurred in one of the eyes of two patients. However, the fellow eye of these patients, which also received a PC-IOL implantation, showed an uneventful postoperative course. The present study indicated that cataract surgery with PC-IOL in patients with severe mental and physical handicaps should be considered as an appropriate and promising application in spite of the various technical difficulties in the pre- and postoperative management of these patients. It is stressed that proper calibration of IOL power immediately before surgery under general anesthesia and small incision techniques are essential for a successful operation in patients with severe mental and physical handicaps.