The use of placebos in therapy or research poses ethical questions. What are the benefits and the costs in ethical terms of condoning deception of the patient or subject? What does the deception mean for the patient's or subject's right to give informed consent to his treatment? Doctors are rightly expected to disclose to their patient facts which would in their judgement best enable him to give informed consent to treatment. On occasion, the degree of this disclosure may be limited (...) by the need to avoid hazarding the success of treatment of an unstable patient whose condition threatens his life, but doctors should have no right to withhold information just to prevent a patient refusing consent to therapy. No such limitation should apply in experiments where full disclosure must operate to enable the subject to give his informed consent. The potential medical benefits for the patient of placebo therapy have to be weighed against all the ethical costs of the deception and dishonesty involved, including the longer term repercussions on doctor/patient trust: similar ethical costs may arise in experiments involving the use of placebos without disclosure of this as a possibility to the subject. Deception is ethically degrading to both parties not only being a breach of trust, but denying the moral autonomy of the patient or subject to make his own choice. The writer concludes that placebos should be used only with full disclosure and consent whether in therapy or in research, and that this need not impede the success of either. (shrink)