A preselected population of 96 patients (67 glaucomas, 29 ocular hypertensions) were followed for an average period of 30 months. Timolol eye drops were administered either alone, in dosage strengths of 0.25 or 0.5% or in combination with other antiglaucoma drugs. 9 patients were lost to follow-up after a mean treatment duration of 15.3 months; glaucoma had been stabilized in all of them. 10 patients had unsatisfactory intraocular pressure control and 7 had to undergo trabeculectomy (9 of these 10 patients had campimetric glaucoma at the beginning of the study), whereas 76 patients had satisfactory intraocular pressure control and, in the majority, stabilization of glaucoma had been obtained. In 77% of this preselected population glaucoma was stabilized over a period of 3 years (i.e. close to two thirds of those starting treatment, 70% of which had campimetric glaucoma).