Background Travoprost has been widely used for the treatment of patients with open-angle glaucoma (OAG) or ocular hypertension (OH). The aim of this study was to evaluate the intraocular pressure (IOP) lowering efficacy of travoprost 0.004% monotherapy in patients previously treated with other topical hypotensive medications, and in previously untreated patients. Methods This open-label, 12-week study in 1651 adult patients with ocular hypertension or open-angle glaucoma who were untreated or required a change in therapy (due to either inadequate efficacy or safety issues) as judged by the investigator was conducted at 6 sites in China. Previously treated patients were instructed to discontinue their prior medications at the first visit. All the patients were dosed with travoprost 0.004% once-daily at 8 p.m. in both eyes for 12 weeks. Efficacy and safety evaluations were conducted at week 4 and 12. IOP measurements were performed at the same time of day at the follow-up visits. Results For patients transitioned to travoprost, mean IOP reductions from baseline in untreated and treated patients with different prior medications at week 12 were: latanoprost, (4.3+/-4.6) mmHg; beta-blocker, (6.3+/-4.0) mmHg; a-agonist, (7.5+/-4.3) mmHg; topical carbonic anhydrase inhibitors, (8.0+/-4.9) mmHg. All mean IOP changes from baseline were statistically significant (P <0.001). No treatment-related serious adverse events were reported in this study. Conclusions In patients treated with other hypotensive medications or untreated, the IOP reduction with travoprost was significant. The results of this study demonstrated the potential benefit of using travoprost as a replacement therapy in order to ensure adequate IOP control. Travoprost administered once daily was safe and well tolerated in patients with glaucoma or ocular hypertension. Chin Med J 2010;123(11):1417-1421