OBJECTIVES: Compare the risk-benefit preferences of patients, parents of juvenile patients and gastroenterologists for Crohn's disease (CD) treatments. METHODS: Panels of CD patients, parents of juvenile patients and gastroenterologists completed a series of choice-format conjoint trade-off tasks with varying efficacy and risk levels. Parents evaluated treatments for their child, gastroenterologists evaluated treatments for three patients (young, middle-aged, elderly). Treatment attributes included daily symptom severity and activity limitations, potential for CD complications, time between flare-ups, systemic steroid use, and three SAE mortality risks: serious infection (SI), progressive multifocal leukoencephalopathy (PML) and lymphoma. Preference estimates were used to calculate the annual SAE-specific maximum acceptable risk (MAR) for various levels of clinical benefit. RESULTS: 342 patients, 105 parents of juvenile patients, and 315 gastroenterologists provided usable data for analysis. For all respondent groups improvement in daily symptom severity was the most important factor in treatment preferences and risk tolerance was greater for treatments with better clinical benefits. Physicians had lower MARs for young patients and higher MARs for the elderly. For middle-aged patients, gastroenterologists' MAR ranged from 0.16% to 0.76% for death or disability from PML, 0.24% to 0.58% for death from SI, and 0.13% to 0.81% for death due to lymphoma. Patients' preferences are similar to that of physicians' preferences for middle-aged patients across most benefit levels. Compared to adult patients, parents have greater risk tolerance for treating severe CD symptoms, and smaller risk tolerance for treating moderate CD symptoms. CONCLUSION: Respondents indicated they are willing to accept defined mortality risks in exchange for clinical efficacy and that acceptance is affected by the degree of benefit, the patient's characteristics and the nature of the SAE. Understanding risk-benefit preferences can assist in identifying appropriate treatments and in informing welfare-enhancing regulatory decisions.