In the last four years we have treated with the mobile argon-laser beam 25 cases of aphakic pupillary block glaucoma (p. b. g.). According to the time of manifestation of the p. b. g. the patients were divided into an "early" and a "late" group. In the "early" group (17 eyes) the glaucoma manifested itself 1--4 days after cataract extraction. In the "late" group (8 eyes) p. b. g. appeared from 4 weeks to 3 years after cataract extraction. In 14 of the 17 cases of the first group we achieved a prompt reformation of the anterior chamber and a considerable decrease of intraocular pressure immediately after laser application. In 3 cases of the first group, where the pupil was under relative or absolute mydriasis before argon-laser treatment, the mobile laser beam failed to produce satisfactory results. In all of the 8 patients of the "late" group a reformation of the anterior chamber was achieved, but in only 4 of them did i. o. pressure normalize owing to extensive anterior synechiae. Laser application left either very slight or no traces at all on the iris. In order to ascertain the actual effect of the laser beam upon the iris, we applied laser under identical conditions in eyes which had no glaucoma but were to undergo enucleation because of choroidal melanoma. The histological examination revealed a slight degree of hyperaemia of the iris as an oedema of the connective tissue, while the iris sphincter did not appear to be affected by laser treatment.