We retrospectively reviewed the records of patients followed for over 4 years after undergoing trabeculotomy to treat primary open-angle glaucoma (POAG) to evaluate the long-term effects of the procedure on intraocular pressure (IOP) control. IOP remained below 15 mm Hg, with no need for postoperative medication in 7 (13.2%) of 53 eyes. IOP was below 15 mm Hg in an additional eight eyes (15.1%) treated with topical medication. Topical medication was needed to maintain IOP between 16 to 20 mm Hg in 23 eyes (43.4%). Oral acetazolamide or additional surgery was needed in 15 (28.3%). A postoperative IOP below 20 mm Hg with or without topical medication was associated with a survival probability of 71.2%. Our results demonstrated that, although trabeculotomy largely failed to maintain an "ideal" postoperative IOP (below 15 mm Hg), it was not associated with severe operative or postoperative complications such as flat anterior chamber. Thus, the procedure probably should be the first choice not only in uncomplicated cases of congenital glaucoma and pseudoexfoliation glaucoma (as previously established), but also in cases of POAG in young patients with only slight damage to the optic disc or visual field and cases with forward movement of the iris-lens diaphragm.