abstract Is it permissible for a doctor or nurse to knowingly administer a placebo in a clinical setting? There is certainly something suspicious about it: placebos are typically said to be ‘sham’ treatments, with no ‘active’ properties and so giving a placebo is usually thought to involve tricking or deceiving the patient who expects a genuine treatment. Nonetheless, some physicians have recently suggested that placebo treatments are sometimes the best way to help their patients and can be administered in an honest way. These physicians conclude that placebo treatments are a perfectly acceptable, and ethically unproblematic, mode of treatment. While I grant the common idea that placebos are deceptive is correct, I argue that widespread misunderstandings concerning why this is so has led proponents of placebo treatments to respond to the charge of deception in a way that misses the mark entirely. My goal in this paper, then, is to develop a precise conception of what makes something a placebo, which in turn will clarify the central charge concerning the ethics of placebo treatment, viz. that it is deceptive.