Purpose To compare the late complications in the Ahmed Baerveldt Comparison Study during 5 years of follow-up. Design Multicenter, prospective randomized clinical trial. Methods setting: Sixteen international clinical centers. study population: Two hundred seventy-six subjects aged 18-85 years with previous intraocular surgery or refractory glaucoma with intraocular pressure of >18 mm Hg. interventions: Ahmed Glaucoma Valve FP7 or Baerveldt Glaucoma Implant BG 101-350. main outcome measures: Late postoperative complications (beyond 3 months), reoperations for complications, and decreased vision from complications. Results Late complications developed in 56 subjects (46.8 ± 4.8 5-year cumulative % ± SE) in the Ahmed Glaucoma Valve group and 67 (56.3 ± 4.7 5-year cumulative % ± SE) in the Baerveldt Glaucoma Implant group (P =.082). The cumulative rates of serious complications were 15.9% and 24.7% in the Ahmed Glaucoma Valve and Baerveldt Glaucoma Implant groups, respectively (P =.034), although this was largely driven by subjects who had tube occlusions in the 2 groups (0.8% in the Ahmed Glaucoma Valve group and 5.7% in the Baerveldt Glaucoma Implant group, P =.037). Both groups had a relatively high incidence of persistent diplopia (12%) and corneal edema (20%), although half of the corneal edema cases were likely due to pre-existing causes other than the aqueous shunt. The incidence of tube erosion was 1% and 3% in the Ahmed Glaucoma Valve and Baerveldt Glaucoma Implant groups, respectively (P =.04). Conclusions Long-term rates of vision-threatening complications and complications resulting in reoperation were higher in the Baerveldt Glaucoma Implant than in the Ahmed Glaucoma Valve group over 5 years of follow-up.