OBJECTIVE To evaluate the efficacy of repeat 360-degree selective laser trabeculoplasty (SLT) in glaucoma patients with prior successful 360-degree SLT. METHODS Retrospective chart review. METHODS Forty-four eyes of 35 patients, > or =18 years of age, with open-angle glaucoma (primary open-angle, pseudoexfoliation, or pigmentary glaucoma), uncontrolled on maximum tolerable medical therapy, underwent an initial 360-degree SLT (SLT1), which was successful for > or =6 months, but eventually lost efficacy and was followed by a repeat 360-degree SLT (SLT2). Patients with prior argon laser trabeculoplasty or other glaucoma surgery, before or during the study period, were excluded. Intraocular pressure (IOP) measurements were recorded before each procedure and 1 to 4 weeks, 1 to 3 months, and 5 to 8 months posttreatment and 15 to 21 weeks after the initial SLT. RESULTS Reduction in IOP after SLT1 and SLT2 was significantly less with repeat treatment at 1 to 3 months, with average decreases of -5.0 and -2.9 mm Hg, respectively (P=0.01), but there were no statistically significant differences between treatments at the other equivalent time points. Using a definition of "success" as > or =20% peak IOP reduction, success rates for SLT1 and SLT2 were not significantly different. There was also no significant difference in eyes that received SLT2 6 to 12 months after SLT1 compared with those that received SLT2 12 months or more after SLT1. CONCLUSIONS Our findings suggest that repeat 360-degree SLT may be safe and effective after an initially successful 360-degree SLT has failed. These results may be achieved as early as 6 months after the first treatment.