Purpose: To assess the safety and efficacy of changing to the travoprost/timolol fixed combination (TTFC) from other mono-or adjunctive therapies. Patients and methods: A prospective, open-label, observational cohort of primary open-angle glaucoma and ocular hypertensive patients whose intraocular pressure (IOP) was uncontrolled on prior therapy or was not on target. Patients were changed from prior mono-or adjunctive treatment at Day 0 to TTFC dosed every evening and underwent active treatment efficacy and safety evaluations at Week 12. Results: In 474/522 (91%) patients who completed this trial an IOP (mm Hg) of 21.9 +/- 2.0 on prior treatment was reduced by TTFC at Month 3: from all prior treatments 5.6 +/- 2.6; from monotherapy 5.9 +/- 2.3; from adjunctive treatments 4.5 +/- 2.9; and from several of the most frequent individual treatments: timolol 5.7 +/- 2.2; latanoprost 6.3 +/- 2.6; and latanoprost/timolol fixed combination 4.4 +/- 1.9. Ocular hyperemia was the most frequent adverse effect (n = 21, 4%). Both patients and physicians preferred TTFC compared to all prior and common individual treatments. The solicited symptom survey showed, following a modified Bonferroni correction (a/5), a reduced incidence with TTFC of ocular pain (P = 0.01) while the prior medicine had a lower incidence of burning on instillation (P < 0.001). Conclusions: Changing patients from prior mono-or adjunctive therapy to TTFC can provide on average a further reduction in IOP while demonstrating a favorable safety profile and a high patient preference.