The phrase "duty of care" is, at best, too vague and, at worst, ethically dangerous. The nature and scope of the duty need to be determined, and conflicting duties must be recognized and acknowledged. Duty of care is neither fixed nor absolute but heavily dependent on context. The normal risk level of the working environment, the healthcare worker's specialty, the likely harm and benefits of treatment, and the competing obligations deriving from the worker's multiple roles will all influence the limits of the duty of care. As experts anticipate the arrival of an avian influenza pandemic in humans, discussion of this matter is urgently needed.