Objective: To determine the incremental cost-effectiveness of brimonidine/timolol versus dorzolamide/timolol for lowering intraocular pressure (IOP). Methods: A cost-effectiveness analysis was performed using clinical data from 2 investigator-masked, randomized, 3-month, parallel-comparison studies performed at 10 sites. In a post-hoc analysis of those patients receiving monotherapy treatment for IOP lowering (either brimonidine/timolol or dorzolamide/timolol) for three months, the proportion of patients at various IOP levels were calculated and statistically compared. A three month supply of each drug was calculated based on their respective WAC price and bottle size (5 ML brimonidine/timolol and 10 ML dorzolamide/timolol). The incremental cost-effectiveness ratio (ICER) was calculated as the difference in drug cost divided by the difference in the percentage of patients meeting the IOP threshold at three months between brimonidine/timolol and dorzolamide/timolol. Results: A 3-month supply of brimonidine/timolol and dorzolamide/timolol were $169.83 and $154.40, respectively yielding a cost difference of $15.44. The proportion of patients at lower IOP thresholds was consistantly higher with brimonidine/timolol compared to dorzolamide/timolol resulting in a statistically significant incremental benefit for the thresholds from less than 17mmHg to less than 12mmHg. The associated ICER s for those thresholds range from $55.12 - $85.75 per the percentage of patients reaching the IOP threshold. Conclusion: We calculated brimondine/timolol to be more cost-effective than dorzolamide/timolol. Given the importance of achieving target IOP, both cost and effectiveness should be considered when evaluating combination therapies for glaucoma.