A follow-up study of 90 eyes in 60 patients subjected to trabeculectomy between 1967 and 1972 showed that intraocular pressure was controlled at the onset in 84% of the eyes, and eventually controlled in over 97%. Only 11% of the eyes required further medication and 5.5% further surgery. Subconjunctival drainage was established by means of a bleb in 91%. Trabeculectomy produced a high significant fall in intraocular pressure (P less than .001) and a parallel rise in aqueous outflow facility. The absolute fall in intraocular pressure was constant whether the preoperative pressure was high or low and whether or not the postoperative pressure remained above 20 mm Hg. This method was virtually free of major operative and postoperative complications when used appropriately; and it can be modified during the operation to deal with peripheral anterior synechiae. The anterior chamber remained formed or, if lost, was speedily re-formed. The anterior chamber rarely flattened postoperatively.