We compared prognostic indicators manifesting within the first 2 postoperative days, with filtration status 3 months following trabeculectomy in 51 primary open-angle glaucoma patients. Patients with an avascular area in the filtering bleb 2 days after surgery had a significantly lower (P less than .05) intraocular pressure (IOP) (12.6 mm Hg) 3 months postoperatively than patients with vascular blebs (16.3 mm Hg). However, neither the height, breadth, or transparency of the filtering bleb, presence of microcysts, anterior chamber depth, nor IOP during the first 2 postoperative days were related significantly to the filtration status at 3 months.