BackgroundThe nature of the relationship between a clinical investigator and a research subject has generated considerable debate because the investigator occupies two distinct roles: clinician and scientist. As a clinician, the investigator has duties to provide the patient with optimal care and undivided loyalty. As a scientist, the investigator has duties to follow the rules, procedures and methods described in the protocol.Results and conclusionIn this article, I present a contextual approach to the investigator-subject relationship. The extent of the investigator's duty (...) to provide the patient/subject with clinical care can vary from one situation to the next, as a function of several factors, including: the research design, benefits and risks of the research; the subject's reasonable expectations, motivations, and vulnerabilities; the investigator's ability to benefit the subject; and the investigator's prior relationship with the subject. These and other factors need to be considered when determining the clinical investigator's obligations to provide clinical care to human research subjects. In some research contexts, the investigator has extensive clinical obligations to the patient/subject; in others, the investigator has minimal ones. (shrink)