Advertising by health care institutions has increased steadily in recent years. While direct-to-consumer prescription drug advertising is subject to unique oversight by the Federal Drug Administration, advertisements for health care services are regulated by the Federal Trade Commission and treated no differently from advertisements for consumer goods. In this article, we argue that decisions about pursuing health care services are distinguished by informational asymmetries, high stakes, and patient vulnerabilities, grounding fiduciary responsibilities on the part of health care providers and health care institutions. Using examples, we illustrate how common advertising techniques may mislead patients and compromise fiduciary relationships, thereby posing ethical risks to patients, providers, health care institutions, and society. We conclude by proposing that these risks justify new standards for advertising when considered as part of the moral obligation of health care institutions and suggest that mechanisms currently in place to regulate advertising for prescription pharmaceuticals should be applied to advertising for health care services more broadly.