Argon laser trabeculoplasty (ALT) was performed on 173 eyes of 126 patients affected by uncontrolled primary open-angle glaucoma. All subjects were phakic. An overall decrease of intraocular pressure (IOP) from baseline of 19.1 ( ± 18) were observed. With linear regression analysis, a positive correlation was found between baseline IOP and percentage IOP fall. The effect of ALT in myopes, hyperopes, younger and older patients was also analyzed. Although a less pronounced IOP fall was observed in the subgroups of higher myopes and of younger patients, no direct relationship could be established between amount of IOP change and age or refraction. In subjects treated bilaterally, a significant correspondence of effect was found between the two eyes.