This study was conducted to determine how phaco-emulsification and intraocular lens (IOL) implantation influenced intraocular pressure (IOP) in eyes with glaucoma, and glaucoma medication requirements postoperatively. A retrospective clinical analysis was undertaken of 226 eyes of 182 glaucoma patients who had undergone phacoemulsification and IOL implantation. IOP on the first day after operation increased from a preoperative mean of 17.1 mmHg (SD +/- 3.9 mmHg) to a mean of 20.7 mmHg (SD +/- 9.0 mmHg). One week after operation the average IOP was 17.4 mmHg (SD +/- 5.5 mmHg). One year after operation the average IOP had declined to 15.3 mmHg (SD +/- 3.1 mmHg). One year after operation 34% of the patients did not need glaucoma medication. If glaucoma is fairly well controlled (mean IOP preoperative 17.1 mmHg) phaco-emulsification alone can result in satisfactory IOP control in eyes with capsular and primary open-angle glaucoma.