Since the first attempt at glaucoma surgery in 1830 many surgical procedures have been devised and adopted depending on the understanding of the aetiology and pathogenesis of the disease. Trabeculectomy, the most recent drainage procedure for glaucoma, has become a widely used, effective, and safe method, particularly for chronic simple glaucoma. Up to 4 years' follow-up of 66 eyes (55 patients) is reported. The findings at 6 months, 1 year, 2 years, 3 years, and 4 years were in agreement with previous reports by other authors. The main postoperative complication was transient hyphaema. Of the total number of eyes, 7 needed miotic drops and 5 required further surgical procedures to control the intraocular pressure.