The aim of this study was to establish the value of trabeculectomy throughout a longer period of time, 5-10 years after the operation. Success of the operations was evaluated by setting the following criteria: postoperative values of IOP < 21 mmHg with or without topical medications, preserved function of the optic nerve checked through the findings of the optic disc and the visual field. Filtering blebs were also examined and visual acuity was analyzed. Between 1990 and 1995, 359 were operated using the method of trabeculectomy at the Department of Ophthalmology, Sestre milosrdnice University Hospital. We were able to examine only 186 eyes thoroughly. Five years after the operation the IOP was < 21 mmHg in 90% of eyes with or without therapy and ten years after the IOP remained regulated in 75% of eyes. We found progression of optic disc atrophy in 17% of the cases, and deterioration of the visual fields in 18% of eyes. Visual acuity was reduced in 62% of the cases and 49% of them was due to cataract. After cataract operation, sight improved in 73 % of the cases.The size or the cystic alterations of the filtering bleb did not have the most significant influence on the value of IOP whereas its healing was directly responsible for failure of the operation. Therefore we consider trabeculectomy to be the method of choice among antiglaucoma operations for now.