The idea that physicians are or should be fiduciaries for their patients is a dominant metaphor in medical ethics and law. This article examines the metaphor and asks several questions. How far does the law play out this metaphor in the way it treats doctors? What are the limits in this way of conceiving the patient-doctor relationship? What limitations or modification on its use may be looming in the future? Although doctors perform fiduciary-like roles and hold themselves out as fiduciaries in their ethical codes the law holds doctors accountable as fiduciaries only in restricted situations. Moreover, private and public groups often expect doctors to work for parties other than patients