Background: This study aims to determine the prevalence, clinical characteristics, and mechanisms of secondary glaucoma in Vogt-Koyanagi-Harada (VKH) disease. We performed a retrospective, observational, and longitudinal study in VKH patients seen from 2001 to 2019. Demographic data, disease stage, glaucoma development, visual outcome, and management were analyzed. Results: A total of 305 eyes from 155 VKH patients, including 114 (74.4%) females and 39 (25.6%) males with a mean age of 38.8± 12.8 years, were analyzed. The median follow-up time was 22 months (range 7-60 months). Secondary glaucoma developed in 67 (22.0%) eyes, most of which had chronic recurrent VKH disease at presentation 43 eyes (62.4 %). Angle-closure was the most observed mechanism of glaucoma in 55 (82.1%) eyes, as shown by the development of peripheral anterior synechiae in 58 (86.6%) eyes and posterior synechiae in 51 eyes (76.1%). The combination of pupillary block and posterior synechiae resulted in iris bombé in 17 (25.4%) eyes with glaucoma. Forty-one (61.2%) eyes with glaucoma required either a laser or surgical procedure to control the intraocular pressure. At the last visit, visual acuity was significantly worse in eyes with glaucoma (p<0.001).Conclusions: As evidenced by the development of anterior and posterior synechiae, the angle-closure disease is a significant cause of secondary glaucoma in eyes with VKH. Eyes with glaucoma are more likely to present in the chronic recurrent stage of the disease. Most of the eyes with glaucoma required a surgical procedure to control intraocular pressure.