Chairpersons of the hospital ethics committees (HECs) and BMT clinicians were compared with regard to their willingness to proceed with allogeneic BMT given select psychosocial risk factors. A self-administered questionnaire was sent to 62 HEC chairpersons at hospitals with an accredited BMT program; the response rate was 37%. Items included background information, followed by six case vignettes from a 2006 national survey on which BMT physicians, nurses and social workers agreed not to proceed with allogeneic BMT on the basis of the following risk factors: suicidal ideation; use of addictive, illicit drugs; history of non-compliance; absence of a caregiver; alcoholism; and mild dementia from early onset of Alzheimer's disease. Opinions regarding transplant differed in one case only, in a patient with mild dementia; 27% of HEC chairpersons recommended not proceeding with BMT, which was significantly lower than that of nurses (68%, Po0.001), physicians (63.5%, Po0.001) and social workers (51.9%, P ¼ 0.05). Qualitative data show patterns of informal reasoning, linking transplant decisions to patient's responsibility for their psychosocial risk factor(s), as well as to medical benefit and outcome.