Approximately 3 million Americans served in the armed forces in Vietnam during the Vietnam War. Some of them (as well as some Vietnamese combatants and civilians, and members of the armed forces of other nations) were exposed to defoliant mixtures, including Agent Orange. Evidence suggests some lasting health effects from these exposures, including certain cancers. This article reviews the evidence on cancer risk after Agent Orange exposure. Data sources include studies of Vietnam veterans, workers occupationally exposed to herbicides or dioxins (since dioxins contaminated the herbicide mixtures used in Vietnam), and Vietnamese populations. The article then reviews clinical issues that arise when caring for cancer patients who may have sustained Agent Orange exposure, or others concerned about such exposure to Agent Orange, such as available benefits programs and sources of information and counseling.