Abstract AIMS: To compare the efficacy of pneumatic trabeculoplasty (PNT) and argon laser trabeculoplasty (ALT) in primary open-angle glaucoma (POAG) uncontrolled with two topical therapies. METHODS: In a randomized, prospective clinical study, 32 patients received in 1 eye PNT or ALT. RESULTS: At 1 month, in PNT- and in ALT-treated eyes respectively, mean intraocular pressure (IOP) decreased by 3 +/- 2.3 and 5.7 +/- 1.7 mm Hg (12.7 +/- 9.6 and 24.4 +/- 7.4%, both paired t test p < 0.001); 5 and 13 eyes (31 vs. 81%, chi(2) test p = 0.013) had an IOP reduction >or=20%, 7 and 1 eyes had an insufficient effect (IOP >20 mm Hg). Only 1 PNT-treated eye had IOP reduction >or=20% until 4 months. At 6 months, 10 ALT-treated eyes (62.5%) had IOP reduction >or=20%; 15 PNT- and 3 ALT-treated eyes had an insufficient effect (94 vs. 19%, p < 0.001). Transient anterior segment side effects, but not visual field or fundus changes, occurred after both treatments. CONCLUSIONS: PNT is less effective than ALT in POAG uncontrolled with two topical therapies.