Background: Decision modeling is commonly used to assess the cost-utility of drugs or technologies.  For a real-world application, models should include aspects of the disease relevant to the patient. In recent years, patient focus groups have been used to help define health utility values. Methods: Hemophilia patients attending the National Hemophilia Foundation’s 61st Annual Meeting were invited to participate in a focus group to inform the development of a decision model, evaluating prophylactic treatment of hemophilia. Patients and caregivers completed questionnaires and provided verbal feedback addressing several open-ended questions, including type and duration of bleeds, disability, impact of treatments on lifestyle and their perceptions about standard utility. Results:  Twenty-one patients or caregivers of children with bleeding disorders attended. Important implications for the model were noted:  a) Patients reported that muscle bleeds can be more painful and last longer (ie, associated with lower utility) than joint bleeds, which are generally considered more disabling; b) Patients reported that the course (utility, improvement) of a typical bleed differs by the type of bleed (joint vs. muscle), not necessarily by bleed severity alone; c) Although patients reported a loss of utility during a bleed, they gradually regained the same level of utility/function, hence disability was not perceived as a linear process;  d) Adult patients reported that nowadays, unlike them, children with hemophilia receiving prophylactic treatment are able to play sports (eg, ice hockey), thereby having better quality of life, an aspect not captured by standard utility instruments; e) Although caregiver-administered instruments for assessing quality of life in children with hemophilia are available, caregivers noted concern about accurately rating their child’s health status based on their experience.  Conclusion: Although qualitative, patients’ perspectives revealed in this focus group demonstrated important utility consequences for the economic model that are not represented in the literature.