Physicians often struggle with ethical issues surrounding intervention in their relatives' health care. Many editorials, letters, and surveys have been written on this topic, but there is no systematic review of its prevalence. An Ovid Medline search was conducted for articles in English, written between January 1950 and December 2010, using the key words family member, relatives, treatment, prescribing, physician, and ethics. The search identified 41 articles (editorials, letters, and surveys). Surveys were reviewed to explore demographics of these treating physicians and reasons for and against intervention. Physicians often intervene directly or indirectly in the health care of relatives. The most common reasons were convenience, cost savings, and the perception of having greater knowledge or concern than colleagues. Lost objectivity, fear of misdiagnosis, and inability to provide complete care were the main considerations against intervention. The characteristics of treating doctors were nonspecific. Most surveys recommend against this practice except for emergencies or minor ailments. This review included only a few surveys with small sample size and only assessed scientific literature written in English after 1950. Survey data may be biased by physicians' self-reporting. In conclusion, most doctors occasionally intervene in their relatives' care. The decision to do so is determined by multiple factors. Physicians should treat only short-term or minor illnesses within their scope of practice. Future research should evaluate doctors' attitudes toward their relatives, medical student feelings about treating family, and intervention frequencies of medical and nonmedical professionals.