OBJECTIVES: Haemophilia is a very expensive disease. This situation becomes extreme when patients develop inhibitors that compromise the effectiveness of treatment, with potential increase of morbidity and mortality. Treatment of haemophilia is the result of interactions between patients, physicians, pharmacists and budget holders, each carrying their own set of preferences. A pilot study was conducted to identify which characteristic of coagulation products are considered more important to treat patients with inhibitors: these characteristics will be included with a price proxy characteristic in a Discrete Choice Experiment, with the objective to elicit preferences and willingness to pay towards treatments of patients with inhibitors. METHODS: Eight characteristics were identified during focus groups with patients and clinicians and rated from 0 (not important) to 10 (very important) by 35 people (adult patients, caregivers, physicians, pharmacists). RESULTS: the following median (mean) scores were found: “viral safety”: 10 (8.9); “time to stop bleeding”: 9.5 (9.0); “risk of anamnestic response”: 9.0 (8.5); “possibility of undergoing major surgery”: 9.0 (8.8); “regular use in prophylaxis”: 9.0 (8.4); “time to pain recovery”: 9.0 (8.3); “number of injections to stop bleeding”: 8.0 (7.9); “time to prepare and give/have the injection”: 7.0 (6.6). All groups of respondents considered as more important “viral safety”, “possibility of undergoing major surgery”, “risk of anamnestic response”, “time to stop bleeding”, while “time to prepare and give/have the injection” was considered the least important. Different preferences were attributed to “time to pain recovery”, considered more important by patients; “regular use in prophylaxis”, considered more important by caregivers. CONCLUSIONS: Viral safety and effectiveness are considered as the most important characteristics in the treatment of haemophilic patients with inhibitors. Different levels of preferences are present between patients, or their caregivers, and physicians. Understanding these differences is important to guide optimal therapeutic strategies in patients with inhibitors.