This paper presents the results obtained in 70 eyes with primary glaucoma, with use of a new fistulizing operation previously described by me.1A fistula is produced by causing the lips of a scleral incision, made as for peripheral iridectomy, to retract by application of a cautery superficially to the wound edges. A preliminary report, based on experience with 42 eyes, indicated that the procedure could be used whenever a fistulizing operation was deemed necessary. It was effective in eyes with either wide or narrow angles and seemed of particular value in neglected acute and advanced narrow-angle glaucoma because of its simplicity and safety. The operation resembles a peripheral iridectomy as performed for narrow-angle glaucoma. Rather than the small conjunctival flap employed for peripheral iridectomy, a large flap of Tenon's capsule and conjunctiva is reflected to the limbus as for any filtering operation. Anab externoincision is made