In an attempt to enhance the success of trabeculectomy in patients under 40 years old, beginning 48 hours after surgery, we injected 5 to 45 mg (mean, 35 mg) of 5-fluorouracil in 10 eyes of six patients. After a mean follow up of 14.9 months (range, 6 to 27 months), intraocular pressure was below 21 mm Hg in 9 of the 10 eyes, with no antiglaucoma medication.