PURPOSE: The purpose of this study is to document the presence of fibrovascular ingrowth into the Ahmed glaucoma valve (AGV) as a cause of AGV failure in the pediatric population. DESIGN: Retrospective case series. METHODS: Retrospective study of six children with histologically documented fibrovascular ingrowth of their AGV, with review of relevant demographic, clinical, and surgical factors. RESULTS: Six patients, two males and four females, with a mean age at AGV placement of 27.5 months (range 1 to 122) were identified with AGV failure, AGV removal, and subsequent histology documenting fibrovascular ingrowth into the valve chamber. Etiology of glaucoma included: trauma, aphakia, angle-closure, aniridia, and infantile. Mean time from AGV implantation to explantation was 23 months (range 6 to 65). Mean intraocular pressure at AGV explantation was 35 mm Hg (range 27 to 48). CONCLUSIONS: Fibrovascular ingrowth of both the pediatric and adult size AGV occurs in children and should be considered in the presence of AGV failure.