The physician-patient relationship is a cornerstone of the medical encounter and has been analyzed extensively. But in many cases, this relationship is altered because patients are unable to make decisions for themselves. In such cases, physicians rely on surrogates, who are often asked to "speak for the patient." This view overlooks the fundamental fact that the surrogate decision maker cannot be just a passive spokesperson for the patient but is also an active agent who develops a complex relationship with the physician. Although there has been much analysis of the ethical guidelines by which surrogates should make decisions, there has been little previous analysis of the special features of the physician-surrogate relationship. Such an analysis seems crucial as the population ages and life-sustaining technologies improve, which is likely to make surrogate decision making even more common. We outline key issues affecting the physician-surrogate relationship and provide guidance for physicians who are making decisions with surrogates.