Purpose To evaluate the long-term outcomes of Ex-PRESS glaucoma filtration surgery and identify risk factors for surgical failure.Patients and Methods: This retrospective single-center study included 139 patients (171 eyes) who underwent Ex-PRESS surgery and were followed for at least 1 year. Surgical success was evaluated using two criteria. Criterion A was defined as a post-operative intraocular pressure (IOP) reduction of ≥ 20% from the preoperative IOP and an IOP of 5-18 mmHg. Criterion B was defined as a post-operative IOP reduction of ≥ 20% from the preoperative IOP and an IOP of 5-15 mmHg. The use of additional glaucoma medications was not considered in the definition of surgical success. The following six potential risk factors were evaluated using a Cox proportional hazards model: (1) age, (2) central corneal thickness, (3) preoperative IOP, (4) glaucoma type (primary open-angle glaucoma or pseudo-exfoliation glaucoma), (5) surgical methods (Ex-PRESS surgery alone or combined with cataract surgery), and (6) history of trabeculotomy.Results Ex-PRESS surgery significantly reduced IOP. The mean preoperative IOP was 24.4 ± 8.9 mmHg. The mean postoperative IOP was 11.3 ± 4.3 mmHg at 5 years and 10.4 ± 4.4 mmHg at 10 years. The 5-year and 10-year surgical success rates were 75.7% and 45.4%, respectively, for criterion A, and 67.8% and 44.1%, respectively, for criterion B. Pseudoexfoliation glaucoma (p = 0.045) and higher preoperative IOP (p = 0.046) were significant risk factors for surgical failure.Conclusions Ex-PRESS surgery requires long-term follow-up, as IOP increased in some patients even after 5 years.