The purpose of this survey in 50 healthy volunteers from a single-centre study was to assess from a questionnaire filled in by the participants, their comprehension and evaluation of the written and oral information and the legal framework, as well as their uncertainty regarding participation, in terms of age, gender and profession. Overall satisfaction with regard to comprehension and oral information was recorded, but 42% of volunteers considered the informed consent form too long and one-quarter of them did not read it completely. Knowledge of the legal framework (20%) did not influence either their understanding or hesitation to participate. The hesitant individuals (26%) more often judged this framework to be reassuring than the non-hesitant individuals (77% versus 38%; p = 0.015). These findings concerned females, medics or paramedics and younger individuals (< or =35 years). In individuals who do not give their consent, it would be interesting to study the reasons for refusal to participate and the influence of the ethical and legal framework in clinical trials in enhancing the patients' partnership in a context of evidence-based medicine.