PURPOSE: To assess rates of surgical revision of glaucoma drainage devices (GDDs) from hypotony owing to overfiltration and its management. DESIGN: Retrospective case series. METHODS: Demographic characteristics, type of GDD implanted, type of surgical revision, and outcomes were obtained from the charts of patients undergoing GDD implantation and > or = 1 subsequent GDD revision in 2002 to 2006. All surgical revisions performed owing to hypotony from overfiltration in the absence of a wound leak were identified. RESULTS: Of 1292 eyes undergoing GDD implantation, 21 (1.6%) developed hypotony owing to overfiltration requiring surgical revision: 15 eyes of 488 (3.1%) with a Baerveldt implant and 6 of 804 (0.7%) with an Ahmed (P=0.002). When including primary and secondary revisions, 6 of 12 eyes (50%) treated by using polyglactin suture ligation were successful (did not require additional surgery) compared with 8 of 10 (80%) undergoing suture ligation using prolene. CONCLUSIONS: Hypotony owing to overfiltration is an uncommon GDD-surgery complication. Understanding how to manage patients who develop this complication can improve patient outcomes.