Background: Aim of this retrospective study was to identify the postoperative complications following trabeculectomy with mitomycin C in patients aged 80 years or older at the time of surgery. Additionally, the corresponding risk factors for postoperative complications were analysed. Material and Methods: During a defined period between 2005 and 2009 all trabeculectomies in this age group at the Department of Ophthalmology, University of Cologne were identified. Second eye surgery and re-trabeculectomies in the same eye were excluded from data collection. Postoperative ocular hypotony (< 6 mmHg) and hypertony (> 20 mmHg), bleeding, corneal erosion, re-surgery and prolonged postoperative duration of hospital stay were defined as complications. Results: One hundred and twenty eyes of 120 patients were included. The mean age was 83.4 years, 62.5% patients were female. Eighty nine percent of the eyes were pseudophakic, the mean visual field defect was - 17.3 dB, the mean preoperative intraocular pressure under pressure-reducing medication was 24.1 mmHg. Considering the perioperative complications there was no significant difference depending on the age (80-85 years, n = 79 and > 85 years, n = 41), depending on the type of anesthesia (general, n = 80 and local, n = 40) or depending on antiplatelet (APT)/anticoagulative (ACT) therapy (APT, n = 55 and ACT, n = 16). The postoperative duration of the hospital stay showed significant correlations with the occurrence of corneal erosions, postoperative ocular hypertony, loss of anterior chamber and choroidal detachment. Conclusions: The postoperative risks of antiglaucomatous filtering surgery did not increase with age or comorbidity. However, even minor perioperative complications had direct implications on the duration of the hospital stay.