We evaluated 30 consecutive patients with glaucoma treated with semi-conductor diode transscleral cyclophotocoagulation to determine the results and complications of this procedure. Twelve months after surgery the mean (+/- SD) preoperative intraocular pressure of 32.5 +/- 10.9 mm Hg (n = 30) had dropped to 20.8 +/- 15.6 mm Hg (n = 19) (P = .018, paired Student's t test), while the mean number of preoperative medications received decreased from 2.0 to 1.8 (P = .060, Wilcoxon's Signed Rank Test). One year after surgery three patients (10%) were unavailable for follow-up, eight (27%) had required other surgical procedures to control the intraocular pressure, 17 (56%) had controllable intraocular pressure of 21 mm Hg or below or received pain relief from the diode laser alone, and two (7%) patients with controlled intraocular pressure had suffered visual loss. Other complications included mild conjunctival hyperemia and uveitis in all patients and mild ocular pain in six patients. This study suggests the usefulness of diode transscleral cyclophotocoagulation in reducing the intraocular pressure for up to 1 year.