We used the semiconductor diode laser to perform transscleral cyclophotocoagulation in 14 patients with glaucoma. Laser settings used for this procedure were 990 milliseconds, 100-microns spot size, and 1,200 mW of power. Applications were placed 1 mm posterior to the surgical corneoscleral limbus and 1 mm defocused toward the ciliary body. The mean preoperative intraocular pressure was 34.8 +/- 13 mm Hg, and the mean intraocular pressure six months after a single treatment session was 24.3 +/- 18 mm Hg (P greater than .001, paired t-test). The mean number of glaucoma medications decreased from 2.2 preoperatively to 1.4 postoperatively. Complications included conjunctival burns and uveitis in 14 patients, and pain in one patient. These results suggested that semiconductor diode transscleral cyclophotocoagulation may be useful as a treatment to reduce the intraocular pressure in patients with glaucoma.