A growing body of scientific research suggests connections between religion, spirituality, and both mental and physical health. The findings are particularly strong in patients with severe or chronic illnesses who are having stressful psychologic and social changes, as well as existential struggles related to meaning and purpose. Recent studies indicate that religious beliefs influence medical decisions, such as the use of chemotherapy and other life-saving treatments, and at times may conflict with medical care. This article addresses the ways physicians can use such information. Spirituality is an area that makes many physicians uncomfortable, since training in medical schools and continuing medical education programs are limited. Not only do most physicians lack the necessary training, they worry about spending additional time with patients and overstepping ethical boundaries. While these concerns are valid, each can be addressed in a sensible way. Taking a spiritual history, supporting the patient's beliefs, and orchestrating the fulfillment of spiritual needs are among the topics this article will address. The goal is to help physicians provide medical care that is sensitive to the way many patients understand and cope with medical illness.