In a retrospective study 97 patients with glaucoma and 16 with ocular hypertension were examined with regard to intraocular pressure (IOP) after extracapsular cataract extraction with implantation of a posterior chamber lens. During the follow-up 39 cases dropped out but 63 glaucoma patients and 11 patients with ocular hypertension were followed for three years. Compared to preoperative IOP 59% of the patients treated previously with Argon laser trabeculoplasty (ALT) had an IOP rise of > 10 mm Hg the day after surgery. The corresponding proportion among medically treated patients was 34% (P = 0.01). A pressure rise of > 10 mm Hg was less frequent among patients treated with one drug than among those treated with two or three (P = 0.05). During follow-up eight patients had a pressure rise which could not be controlled medically and they had to undergo additional ALT or surgery. All eight had been treated with ALT or with glaucoma filtering surgery prior to the cataract operation. After three years observation of 63 of the glaucoma patients, 63% were having less medical therapy than preoperatively, 30% an equal amount and 7% more; 49% (31 of 63) were still without any therapy. In the group of patients who preoperatively were only treated medically, no definite increase in therapy was needed in the long term.