Objective: Treatment preferences of patients with hemophilia and inhibitors have not been well documented. This study sought to identify treatment attributes most important from a patient/caregiver perspective in the U.S. Methods: A discrete choice experiment was conducted to elicit treatment preferences. Hemophilia patients with inhibitors or their caregivers completed a written survey that elicited preferences for treatment features and levels synthesized from the medical literature such as: risk of viral transmission, rise in inhibitor titer, reduction in thromboembolic events, number of infusions, preparation time, infusion time/volume, time required to stop bleeding/alleviate pain, prophylaxis use, major surgery use, and medication cost. Best-worst case scaling was used to derive preferences. Relative importance (RI) of preferences was modeled using a multinomial logit function. Results: Most respondents were male (96.1%) with a mean age of 20.7 years (SD=18.8). Most patients were hemophilia type A (88.5%) and the majority (88.5%) considered their disease “serious.” The three most important patient-identified features were: time required to stop bleeding (RI = 19.3), possibility that the level of inhibitor may rise (RI = 14.3), and risk of contracting a virus from the product (RI = 13.5). Conclusion: Inhibitor patients and caregivers have specific treatment preferences based on product features. Overall, patient preferences were similar to physicians (Lee, 2008), although patients placed more importance on the risk of viral transmission, whereas physicians placed more on the time to alleviate pain. In contrast, other research (Mantovani, et al., 2005) suggests greater importance of perceived viral safety among both physicians and pharmacists relative to patients.