OBJECTIVES: To investigate attitudes to clinical trials in non-cancer trial participants. DESIGN: Questionnaires at entry, during, and after participation in a clinical study. SETTING: Participants in: (i) ROC: a clinical study comparing systemic interferon-alpha-2A treatment vs. prednisolone enemas in ulcerative colitis; and (ii) MRCRUC: a clinical study investigating low-field magnetic resonance imaging as a new modality for the evaluation of patients with inflammatory bowel disease. SUBJECTS: Thirty-two patients in ROC and 47 patients in MRCRUC. OUTCOME MEASURES: Attitudes towards different aspects of clinical research. RESULTS: The majority found scientific testing of clinical methods necessary, having positive attitudes towards both participation by themselves and others. The creation of a personal moral problem by denying participation was rejected by a large majority, and still both personal and altruistic motives for participation were highly rated. An important motive for accepting inclusion was the expectation of being 'a special patient' during the trial. The presence of research ethics committees controlling clinical research had a significant positive impact on decisions to participate, and drawing lots and blinding were found problematic by only a minority. Patients valued their satisfaction with participation in the trials highly, and would almost all accept a request to participate in future trials. The most important reason for this was a feeling of receiving better care and information than expected outside a trial setting, primarily determined by the patients seeing only one physician during the trials. A pronounced wish to obtain follow-up information was expressed. CONCLUSION: Attitudes towards medical research are positive with both altruistic and nonaltruistic motives for participation. Expectations of being treated as 'a special patient' in the trial were important in accepting to participate. Seeing the same physician at control visits was an important factor for satisfaction with participation.