A conflict of interest (COI) is a set of conditions in which professional judgment concerning a primary interest may be influenced by a secondary interest. A COI should be considered to exist if the influence of the secondary interest appears to exist, even if it does not.
 Primary interests of a physician may be, depending on the situation, the welfare of the patients, research validity, and education of medical students. A secondary interest is not always financial gain (financial COI), but a non―financial interest, such as reputation, promotion, competition, and even an inquiring mind, may interfere with the primary interest (non-financial COI).
 After the Gelsinger case was reported in 1999, financial COI of researchers first drew attention in the international community. In this context, the primary interest is research validity, including the safety of participants, and the secondary interest is financial gain. There have been several famous cases of research misconduct overseas, which were likely affected by financial COI. Japan is no exception; research misconduct involving a pharmaceutical company and researchers in several medical schools led to a strict management policy of financial COI in clinical research, and enactment of the Clinical Trial Act in 2017. It is difficult to ensure research integrity by managing financial COI. However, research integrity may be threatened by researchers who seek more impactful research results and papers.
 COI is not only an issue in the context of research. Management of financial COI is becoming more important in clinical practice. Indeed, coverage of the relationship between physicians and pharmaceutical companies is increasing. The Japanese media recently reported on the free meals provided at new drug briefings by pharmaceutical companies in addition to funding physicians. COI management is not just required in research or clinical practice. In the field of medical education, the guidelines for managing COI were published in 2019 in Japan.
 Primary interests of a physician can conflict with each other. The relationship between physicians and patients in clinical practice cannot directly translate into the relationship between researchers and subjects in research or between teachers and materials in medical education. It should be noted that patient participation in clinical research and medical education may undermine their best interests in clinical practice.
 <Author's abstract>