OBJECTIVES: This study evaluated the impact of Selective Serotonin Reputake Inhibitor (SSRI) Step Care program on prescription drug utilization and expenditures. METHODS: Using pre-post with control group study approach, prescription records from October 2003 to April 2005 were obtained from pharmacy claims database in a pharmacy benefit management organization. The study group comprised of patients enrolled in SSRI Step Care, while the control group comprised of those not enrolled in this program. Number of prescriptions dispensed and total costs per member per month (PMPM) for both targeted brand drugs and shift-to-generic drugs were compared between the study and control groups. RESULTS: The study group included 62,451 eligible lives, and the control group included 341,971 lives. From the pre to post period, in the study group, the average number of prescriptions per month per thousand eligible lives and the average PMPM total costs decreased by 37.5% (from 26 to 16.26) and 31.3% (from $2.25 to $1.54) for the target drugs, and increased by 48% (from 11.7 to 17.3) and 15.4% (from $0.79 to $0.91) for the shift-to-drugs respectively. In the control group, however, the average number of prescriptions and the average PMPM costs increased by 18.3% (from 21.18 to 17.31) and 13.4% (from $1.95 to $1.69) for the target drugs, decreased by 8.6% (from 10.4 to 9.5) and 25% (from $0.82 to $0.62) for the shift-to-drugs. SSRI Step Care was estimated to result in $0.41 PMPM cost savings in the target drugs but $0.31 PMPM cost increase in the shift-to-drugs, and a net PMPM total cost savings of $0.10. CONCLUSIONS: SSRI Step Care was found to shift prescription drug utilization from expensive brand names to low cost generics. A medication management program such as SSRI Step Care has been shown to lower prescription drug expenditures.