Nine postkeratoplasty eyes with persistent intraocular pressure (IOP) elevation were treated under an investigational protocol by transscleral YAG cyclocoagulation (TSYCC). All eyes were using the maximally tolerated antiglaucomatous medical therapy. Some eyes also had prior antiglaucomatous surgery, including cyclocryotherapy. All of these eyes were considered poor candidates for filtration. Laser applications were applied in a single session at 32 to 36 equally spaced locations throughout 360 degrees, 2.5 mm posterior to the limbus. The energy employed was between 7 and 10 joules at each site. Total energy varied between 256 and 352 joules per eye. The results and complications associated with this procedure are described in nine eyes with a minimum follow-up of 3 months and a median follow-up of over 6 months. Pressure control was achieved in all eyes. At the energy levels employed, hypotony (IOP less than 3 mm Hg) developed in two of the nine eyes, both of which had prior cyclocryotherapy. IOP was between 5 and 19 mm Hg in the remaining eyes. One of these required further medication (betaxolol) to obtain IOP less than 20 mm Hg, and one other developed a late pressure elevation due to pupillary block. Although these results confirm the efficacy of TSYCC, our outcomes suggest that total energy should be limited to less than 256 joules at the time of initial treatment in order to reduce the incidence of hypotony. Eyes with prior cyclodestructive therapy appear most likely to develop hypotony and should, accordingly, be treated with reduced total energy. Patent iridotomies are required in pseudophakic eyes, as pupillary block can develop due to fibrinous iridocyclitis.