The shared values, beliefs, and behaviors by which people interpret life events are what we call culture. More than medical science, culture determines how people react to illness and death. Science may determine which drug or surgery best treats the disease, but culture often determines how the health professional best treats a patient with the disease. Culture influences when the patient believes he is ill, which treatments he accepts, and which results he prefers. Because culture surely affects illness outcomes, health professionals must not ignore it.This project received financial support from the Mexican American Medical Treatment Effectiveness Research Center and the Aging Research and Education Center at The University of Texas Health Science Center and from the Ecumenical Center for Religion and Health, San Antonio. Presented in an earlier version at the Seventh Annual David C. Thomasma, Ph.D., Memorial International Bioethics Retreat, Medical Faculty, University of Padova, and Fundazione Lanza, Padova, Italy, 26 June 2004; presented at the Second International Conference on Clinical Ethics Consultation, Basel, Switzerland, 19 March 2005; and accepted for presentation at the national meeting of the Society of General Internal Medicine, New Orleans, Louisiana, 13 May 2005. Erika Blacksher, John Stone, Susan Bagby, and David J. Doukas thoughtfully critiqued earlier drafts of this article. Andrew K. Diehl and Helen P. Hazuda critiqued a research abstract of the material. I thank all these people for their many helpful suggestions.