OBJECTIVE: The perception persists among employers and benefit managers that the addition of sildenafil citrate adds significant cost to their prescription plans. A Disease Therapy Evaluation is a focused analysis of a drug's performance in a target patient population and provides healthcare managers with information that may lead to better decisions for the individual patient as well as the healthcare organization. The analysis presented here evaluates the per member per month (PMPM) cost of sildenafil without restriction limits on the quantity of tablets dispensed. METHODS: This retrospective review covered all sildenafil claims of employees obtained from prescription benefit managers. Prescription claims were obtained for a 6-month interval from December 1999 to May 2000 and imported into an Access database for abstraction of required data. RESULTS: Data were combined from 4 prescription plans (3 from the Midwest, 1 from the West Coast) with 361,237 members overall. There were 3477 sildenafil claims in the 6-month period, made by 1493 patients (representing 0.4% of all members). Most of the prescriptions were for the 50-mg (range for 4 plans, 45%-62%) and 100-mg doses (37%-65%) of sildenafil, with 1% to 2.5% for the 25-mg dose. On average, 6 to 11 tablets were dispensed at a time, with a range from 1 to 100 tablets. The average cost per prescription varied from a low end of $50 to a high end of $88; the PMPM cost ranged from $0.03 to $0.24. CONCLUSIONS: The actual PMPM cost is markedly lower than the expected projections, despite the fact that no quantity limits were imposed. The costs shown here do not take into account any rebates or other contracting benefits. Thus, employers may wish to consider the addition of sildenafil to their benefit package, as it may increase employee satisfaction without a large impact on the budget.