OBJECTIVES: To explore how participants evaluate and complete the choice tasks in Discrete Choice Experiments (DCE), with special attention to the impact of educational level and health literacy.  METHODS: Two existing DCE questionnaires on rotavirus vaccination and prostate cancer screening served as a case for the current study. In total, 70 participants were sampled based on educational level (35 per case study). During structured interviews, participants completed five choice tasks aloud. Interviewers monitored how participants read the choice tasks, how they interpreted the included risk attributes and what decision strategy they used to make their decision and if the monotonicity and continuity axioms hold.  RESULTS: The majority of the participants read all the attributes within each choice task.  Nearly all participants chose the scenario with the optimal attribute levels (monotonicity axiom). In accordance with the continuity axiom, most participants mentioned three or more attributes when motivating their decisions. Overall, higher educated and literate participants more often included three or more attributes when motivating their decision and used trading between attributes more often as a decision strategy.  CONCLUSIONS: The majority of the participants complete a DCE as presumed by its underlying methodology. However, the assumptions did not hold for a subset of lower educated and less literate participants. Based on participants’ age, educational level and health literacy additional measures should be undertaken to enhance participants’ understanding of the attributes, the attribute levels and the choice tasks in a DCE.