We analyzed the long-term success of argon laser trabeculoplasty (ALT) performed in 237 eyes of 175 patients diagnosed with primary open-angle glaucoma and followed for up to 11 years (maximum, 132 months) after treatment. The cumulative proportion of success, defined as the avoidance of glaucoma surgery or an intraocular pressure never exceeding 22 mm Hg, was calculated throughout follow up using the Kaplan-Meier life-table analysis. The success rates were: 78% at 1 year (n = 205), 71% at 3 years (n = 139), 61% at 5 years (n = 73), and 40% at 10.5 years (n = 19). Our data confirm previous reports of the high initial success rate of ALT, followed by a time-dependent decrease in its efficacy.