We used the Ahmed valve for the treatment of 142 eyes with high-risk glaucoma. The glaucoma was neovascular in 74 cases, aphakic or pseudophakic in 19 eyes and occurred after previous faliure of filtering surgery in 49 eyes. Preoperative mean IOP was 31.6+/-10.4 mmHg under topical and/or systemic treatment. The success rate (IOP<22 mmHg with only topical treatment) was 56.3% with a mean follow-up of 32.4 months. Complications were fewer and milder compared with those reported for other types of drainage implants and for other types of antiglaucoma procedures.