OBJECTIVE To evaluate the long-term results and complications of ahmed glaucoma valve (AGV) implantation in refractory glaucoma. METHODS A retrospective review of 13 patients (13 eyes) with refractory glaucoma who underwent AGV implantation and had a minimum follow-up of 18 months was performed. All patients underwent a complete ophthalmologic examination and intraocular pressure (IOP) measurement before surgery and at 1 month, 3 months, 6 months, 1 year after surgery and yearly afterwards. Complications and the number of antiglaucoma medications needed were recorded. RESULTS Mean age was 27.3±16.0 years. All eyes (100%) had at least one prior incisional surgery. Mean follow-up was 61.3±30.8 months. IOP was reduced from a mean of 35.0 ±7.0mmHg to 18.2±7.9mmHg at 12 months and to 17.0±4.1mmHg at 96 months (P<0.05) with a lower number of medications from baseline, 76.9% patients required additional procedures to achieve the success criteria set by previously published series. The most common complications were encapculated cyst formation in eight eyes (61.5 %) and tube exposure in four eyes (30.8%). CONCLUSIONS Encapsulated cyst formation was the most common complication which hindered succesful IOP control after AGV implant insertion for refractory glaucoma. Despite cyst excision with anti-fibrotic agents, successful IOP reduction was not achieved in 76.9% of the patients without antiglaucoma medication.