In 34 eyes with various types of glaucoma, cyclodialysis implants were used to produce reduction of intraocular pressure. The average reduction of pressure in the 14 eyes with chronic simple glaucoma (phakic and aphakic) was from 36 mm Hg preoperatively to 15 mm Hg postoperatively. Six of the 14 have since required some medication. The average facility of outflow preoperatively was 0.17 and postoperatively was 0.22. The principal mode of action of the cyclodialysis implants was found to be decreased aqueous formation. A long-term follow-up of these patients has been undertaken.