Background In current Western medical ethics, patient-centered medicine is considered the norm. However, the cultural background of collectivism in East Asia often leads to family-centered decision-making. In Japan, prior studies have reported that family-centered decision-making is more likely to be preferred in situations of disease notification and end-of-life decision-making. Nonetheless, there has been a recent shift from collectivism to individualism due to changes in the social structure. Various personal factors have also been reported to influence moral decision-making. Therefore, this study (...) examined whether the current trend in attitudes of healthcare decision-making in Japan is family-centered or patient-centered among the general public and physicians. In addition, the personal factors that influence this tendency were examined.Methods Three vignettes on disease notification and two vignettes on decision-making during end-of-life care were created, and 457 members of the public and 284 physicians were asked about their attitudes (behavioral intentions) regarding these vignettes.Results Approximately, 95% of physicians were patient-centered in explaining the patient’s severe medical condition. However, approximately 80% of physicians emphasized the wishes of the family over patient wishes when making life-sustaining decisions. Nearly half the general public emphasized the patient’s wishes in the explanation of a severe medical condition and in life-sustaining decisions. In both the public and physician groups, personal factors, particularly the presence or absence of a disease under treatment and prior caregiving experience, influenced ethical attitudes toward medical treatment decisions.Conclusions In relatively low-conflict situations, such as the announcement of a patient’s medical condition, physicians tended to be patient-centered, while they tended to be family-centered in situations of strong conflict in withholding life-sustaining treatment. The fact that personal factors influenced the family-centered response in situations of strong conflict highlights the importance of not only acquiring knowledge of medical ethics but also learning to fairly apply this knowledge in practice. (shrink)