OBJECTIVES: COX-2 Inhibitor Step Care program is designed to promote the use of traditional NSAIDs as a first line agent before a COX-2 inhibitor is used. This study evaluated the impact of this program on COX-2 inhibitor utilization and expenditures in a pharmacy benefit management organization. METHODS: Using pre-post with control group study design, prescription records from January 1, 2003 to October 31, 2004 were obtained from Walgreens Health Initiatives' pharmacy claims database. The study group comprised of three employer groups enrolled in COX-2 Step Care in September 2003, while the control group comprised of all other clients not enrolled in the program. Number of prescriptions dispensed and total costs per member per month (PMPM) were analyzed. PMPM cost savings were calculated using formula: Y'=Yst0*Rct-Yst1, where st0 and st1 represent actual pre and post PMPM total costs in study group and Rct is the ratio of PMPM pre and post total costs in control group. RESULTS: The study group included 166,719 lives, and the control group included 768,836 lives from 227 clients. From the pre to post period, in the study group, the average number of prescriptions per month and the average PMPM costs decreased by 4.7% (from 1,842 to 1,755) and 8.7% (from $1.38 to $1.26) respectively. In the control group, however, the average number of prescriptions and the average PMPM costs increased by 42.5% (from 9,034 to 12,875) and 16.5% (from $1.62 to $1.89). After comparing the trend of COX-2 inhibitors in these two groups, COX-2 Step Care was estimated to result in $0.35 PMPM and $700,220 annualized cost savings for the three employer groups. CONCLUSIONS: COX-2 Step Care led to a decrease of prescription utilization and savings in PMPM total costs and may be an effective option in controlling prescription drug expenditures.