To compare the long-term success rate of selective laser trabeculoplasty (SLT) versus argon laser trabeculoplasty (ALT). Retrospective chart review. One hundred ninety-five eyes of 195 patients with uncontrolled open-angle glaucoma (OAG), of which 154 eyes underwent ALT and 41 eyes underwent SLT and were followed up for a maximum of 5 years. The SLT patients were treated with the frequency-doubled q-switched neodymium:yytrium-aluminum-garnet laser (532 nm). Approximately 50 to 55 nonoverlapping spots were placed over 180 degrees of the trabecular meshwork at energy levels ranging from 0.6 to 1.0 mJ per pulse. The ALT patients were treated with the argon blue-green laser with between 45 to 55 adjacent, nonoverlapping spots over 180 degrees of the trabecular meshwork at 470 to 1150 mW of energy per pulse. The success rates were defined by criterion I and criterion II. Success by criterion I was defined as a decrease in intraocular pressure (IOP) of 3 mmHg or more with no additional medications, laser, or glaucoma surgery. Criterion II had the same requirements as criterion I, except that a 20% or more IOP reduction was required for success. The mean follow-up time was 37.4+/-14.7 months for patients in the SLT group and 33.6+/-17.0 months for patients in the ALT group. The long-term success rate was not significantly different between the ALT and SLT groups by either criterion (Kaplan-Meier survival analysis log-rank P = 0.20 by criterion I and P = 0.12 by criterion II). When comparing patients with and without previous ALT, there was not a statistically significant difference in the patients treated with SLT by either criterion (log-rank P = 0.37 by criterion I and P = 0.39 by criterion II). In eyes with primary OAG that are receiving maximally tolerated medical therapy, SLT was found to be as effective as ALT in lowering IOP over a 5-year period. However, long-term data reveal that many of the glaucoma patients treated with SLT and ALT required further medical or surgical intervention. Whether SLT has better long-term success than ALT in repeat laser trabeculoplasty treatments remains unclear.