Sixteen eyes requiring surgical reformation of the anterior chamber (AC) in our Unit from December 1987 to August 1991 were studied retrospectively to determine the incidence of the problem in our hospital and to evaluate the operative measures used to restore the AC. The mean preoperative AC depth of these 16 eyes was 1.92 mm (range, 1.50 to 2.50 mm). Nine had a history of angle-closure glaucoma. Poor surgical technique was a contributing factor in the development of a flat AC in 3. Of the remaining 13 eyes, 11 had a trabeculectomy with a fornix-based, and 2 with a limbus-based, conjunctival flap. Wound leaks occurred in 10 eyes with fornix-based flaps, but in none of the eyes with limbus-based flaps. Factors associated significantly with the development of flat AC following trabeculectomy were: a preoperative shallow AC, a history of angle-closure glaucoma, and the use of a fornix-based conjunctival flap. Avoiding wound leakage when performing trabeculectomy in eyes with a shallow AC or a history of angle-closure glaucoma by using a limbus-based flap may help prevent postoperative flat AC.