OBJECTIVES: To assess whether different methods of asking for the willingness to pay (WTP) lead to different outcomes. METHODS: Sixty people from the general population were asked for their WTP for a new drug relieving breakthrought cancer pain by a trained interviewer. All the individuals answered WTP questions posed in three different randomised ways with the open-card method. First, they gave their WTP as patients, under certainty of needing the drug (use or consumption value of the good). Second, they gave their WTP for a private insurance (option value) given a probability of 10% of needing the drug one day. Last, they gave their WTP as contributors by paying taxes (existence value). The hypothesis of the research was that the role adopted by the respondent in the hypothetical situation described for each method influences results. We expected the WTP for the drug with the simple method (under certainty) to be lower than the WTP with the private insurance method and the latter to be lower than the WTP with the contributor method, as the different values of the good should be cumulative. RESULTS: The duration of the interview was between 20 and 25 minutes. Data analysis showed that the different methods have an influence on the WTP for the drug and that certain sociodemographic characteristics of the individuals have an impact on study results. The relevance of the differences found will be discussed during the presentation. CONCLUSIONS: Different methods of asking for the WTP lead to differences in outcomes.