<i>Aims:</i> To compare the efficacy of pneumatic trabeculoplasty (PNT) and argon laser trabeculoplasty (ALT) in primary open-angle glaucoma (POAG) uncontrolled with two topical therapies. <i>Methods:</i> In a randomized, prospective clinical study, 32 patients received in 1 eye PNT or ALT. <i>Results:</i> 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%, χ² test p = 0.013) had an IOP reduction ≥20%, 7 and 1 eyes had an insufficient effect (IOP >20 mm Hg). Only 1 PNT-treated eye had IOP reduction ≥20% until 4 months. At 6 months, 10 ALT-treated eyes (62.5%) had IOP reduction ≥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. <i>Conclusions:</i> PNT is less effective than ALT in POAG uncontrolled with two topical therapies.