In June 1984 the authors started a prospective study on the treatment of open-angle glaucoma with argon laser trabeculoplasty. The technique used was to treat 180 degrees of the anterior nonpigmented part of the trabecular meshwork with 80 to 100 burns. For retreatment the posterior pigmented part of the trabecular meshwork was coagulated with 80 to 100 burns. The burns were always applied to the pretreated half of the meshwork. At present the study includes 47 eyes treated posteriorly. Of these cases 12 eyes required retreatment. Five eyes had previously undergone an unsuccessful trabeculectomy. The preliminary results are satisfactory. The average reduction in intraocular pressure was 5.9 mm Hg; the mean intraocular pressure before therapy was 23 mm Hg. In 8 cases the trabeculoplasty failed, making a fistulating procedure necessary. The treatment was always well tolerated and there were only minor side effects which never led to any lasting damage.