In order to determine if post-traumatic angle recession is a risk factor for failure of glaucoma filtering surgery independent of age or race, the surgical results of trabeculectomy performed in 35 consecutive patients with angle recession glaucoma were compared with those of 35 matched patients with primary open angle glaucoma. A postoperative intraocular pressure of < or = 21 mm Hg (with or without glaucoma medication) was found in 15 of the 35 (43%) patients with angle recession glaucoma compared with 26 of the 35 (74%) patients with primary open angle glaucoma. The long term success of trabeculectomy was significantly worse in angle recession glaucoma when the results were analysed using Kaplan-Meier survival curves. Bleb failure occurred a mean period of 3.1 (SD 1.2) months after trabeculectomy in angle recession glaucoma compared with 9.4 (5) months in primary open angle glaucoma (p < or = 0.001). The finding that posttraumatic angle recession is a risk factor for failure of trabeculectomy, supports the use of antimetabolite therapy to suppress fibrosis after trabeculectomy in these patients.