OBJECTIVES: To determine how different factors related to benefit design impact the utilization and costs of PDE-5 inhibitors including vardenafil, tadalafil and sildenafil in adult males. METHODS: Pharmacy claims from a large, private pharmacy benefit management company over a 2-year period from October 1, 2002 to September 30, 2004 were analyzed. PDE-5 utilization, average of age of database population and PDE-5 users, and PMPM were evaluated. RESULTS: The average PMPM for PDE-5 agents was $0.16 over the entire study period with an average of 5.7 pills/rx. The average age of patients for different benefit designs ranged from 52 to 68 years while the sample population age ranged from 24 to 48 years. Plans with no PDE-5 agent on formulary had an average PMPM of $0.08 vs. $0.22 in those with at least one PDE-5 on formulary. Copays for open formulary incentive plans with PDE-5's on 2nd tier were approximately $10 less than PDE-5s on 3rd tier while plan sponsored PMPM costs were similar ($0.17 vs. $0.18). This was attributed to a lower quantity dispensed per prescription (4.5 vs. 6.9). Similar trends were found for closed formulary plans where PDE-5s were on formulary vs. not on formulary (PMPM of $0.03 vs. $0.02). Differences in plan sponsored PMPM costs for open formulary, 1-tier vs. 2-tier plans were attributed to differences in member copays ($3.60 vs. $18.63) and not utilization (6.1 vs. 6.4 pills/rx). CONCLUSION: Despite a younger overall population, PDE-5 utilization was utilized in the 50+ age group regardless of benefit design or restrictions. Plan sponsors can expand access to PDE-5 agents and at the same time limit their PMPM costs with quantity limits.