AIM:To evaluate and compare the effects of Travatan and Betagan in the treatment of primary open angle glaucoma.METHODS:Forty-six patients with primary open angle glaucoma were enrolled in this study from December 2008 to December 2010.The patients were divided into two groups.Patients in proup A were prescribed with Travatan one drop every night and group B with Betagan one drop everynight.All the patients were treated for 12 weeks and were followed up every month.Intraocular pressure was measured at five time points before and every follow up day after treatment,and side effects of the two drugs,if any,were recorded.Data were analyzed by using the SPSS 16.0 software.RESULTS:The average intraocular pressure was significantly reduced 12 weeks after treatment in both groups.The average intraocular pressure in group A decreased from 24.3±2.02mmHg to 16.1±1.34mmHg,while that in group B decreased from 24.99±1.38mmHg to 15.56±0.68mmHg.The decreasing rate of two groups was 36.7% and 35.8%,respectively.The intraocular pressure changes at mid-night(12:00pm) were bigger in group A than in group B(F=4.25,P=0.045),but there was no significant difference in other time points between the two groups.No obvious side effect was observed.CONCLUSION:Both Travatan and Betagan could lower the IOP effectively and stably in the treatment of primary open-angle glaucoma,and could be tolerated well without obvious side effects.Travatan could reduce intraocular pressure more than Betagan at mid-night.