Just as patients may refuse treatment, they also may request treatment, including treatment to prolong life. Physicians have a strong obligation to respect a competent patient’s request, an advance directive, or a surrogate’s decision to prolong life. However, certain relevant limitations exist. Physicians are not obliged to provide physiologically futile treatments—that is, treatments that cannot produce the desired physiologic change. Before withholding or withdrawing treatment, physicians should be as sure as possible that it is futile, and they should have a full, open discussion with the patient or the surrogate about the nature and extent of the futility of the treatment. If a requested treatment entails a loss of function, mutilation, or pain disproportionate to benefit, the physician is not obliged to provide it. Also, a physician who has a conscientious objection to a requested treatment is not obliged to provide it. The physician should explain all treatment options and the physician’s position regarding them. If the patient wishes, the physician should arrange an orderly transfer to another physician of the patient’s choice.