We conducted a short-term prospective clinical study to evaluate Q-switched neodymium-YAG laser iridotomy in 33 eyes with pupillary block glaucoma in which the argon laser was unable to create an iridotomy. These eyes had chronic angle closure glaucoma (11 eyes), acute angle closure glaucoma (five eyes), pseudophakic pupillary block (seven eyes), uveitic pupillary block (three eyes), and contralateral eyes (five eyes); also included were both eyes of a patient with a head tremor. In all eyes, a patent iridotomy was created in one treatment session, with a mean of 5 +/- 5 pulses and a mean total energy of 55 +/- 120 millijoules. Complications included iridotomy closure (two eyes with preexisting active uveitis), focal nonprogressive corneal opacities (six eyes), and minimal bleeding from the iridotomy margin (12 eyes). Q-switched neodymium-YAG laser iridotomy appears to be an effective next step in the management of pupillary block glaucoma prior to surgical iridectomy when argon laser iridotomy fails.