OBJECTIVE To evaluate the efficacy and safety of latanoprost/timolol maleate fixed combination (LTFC) given once daily vs the concomitant therapy of brimonidine twice daily and latanoprost once daily in primary open-angle glaucoma or ocular hypertensive subjects. METHODS A prospective, double-masked, active-controlled comparison in which qualified subjects had all glaucoma medicines discontinued for 1 month and then were randomized to either LTFC or brimonidine and latanoprost concomitant therapy for 6 weeks. They were then switched to the other treatment regimen. The intraocular pressure (IOP) was measured at 0800, 1200, and 1600 h at baseline and at the end of Periods 1 and Period 2. RESULTS In 32 subjects, the diurnal curve of the untreated IOP of 26.0+/-3.4 decreased to 17.8+/-2.5 on LTFC and 17.2+/-2.8 mmHg on brimonidine and latanoprost (P=0.31). At 0800 and 1600 h, the IOPs were statistically similar between the groups (P>0.05). At 1200 h the latanoprost and brimonidine treatment IOP was statistically lower (16.2+/-3.2) than LTFC (18.0+/-2.8 mmHg). However, the reduced IOP from untreated baseline was not statistically different at each time point and for the diurnal curve for each therapy (P<0.05). Safety was similar between groups for both solicited and unsolicited side effects (P>0.05). CONCLUSIONS This study suggests that LTFC and concomitant therapy of brimonidine and latanoprost provide statistically similar diurnal IOP reduction from an untreated baseline.