OBJECTIVE To compare the postoperative outcomes and complications of glaucoma drainage device (GDD) surgery in pediatric (<18 years old) and adult patients. METHODS Retrospective, comparative study including all patients who underwent Baervedlt or Molteno device surgery by the same surgeon. Success criteria included postoperative intraocular pressure (IOP) between 6 and 21 mmHg and a 20% reduction from baseline. RESULTS Fifty-two children (69 eyes) and 130 adults (145 eyes) were included. Mean IOP and number of medications were significantly reduced postoperatively in both groups. Overall failure rate was similar in children and adults. However, GDD failed earlier in adults than in children. Hypotony was the most common complication in both groups in the first 6 months postoperatively. Later on, bleb encapsulation was more frequent in children, while corneal decompensation tended to be more frequent and occurred earlier in adults. Children also had a higher rate of infectious endophthalmitis and required tube repositioning more frequently than adults. CONCLUSIONS GDD surgery presents different postoperative challenges in children and adults, and the surgeon should remain vigilant for complications throughout the postoperative period, especially for signs of endophthalmitis or bleb encapsulation in pediatric patients. On the other hand, adults may be more prone to early corneal decompensation.