A five-year follow-up of argon laser trabeculectomy in a group of 28 male patients with bilateral patients with bilateral primary open-angle glaucoma showed an overall mean pressure drop of 10.3 mm Hg in treated eyes. Twenty percent of the treated eyes had a pressure less than 20 mm Hg up to two years after treatment. No specific laser parameters were associated with pressure lowering. The pressure drop appears more patient dependent than treatment dependent. A randomized clinical trial is suggested.