As practitioners of pulmonary and cardiac medicine, many of us have no doubt been asked by our patients who smoke about so-called “electronic cigarettes” (e-cigarettes). These devices, termed electronic nicotine delivery systems (ENDS) by the World Health Organization, have been available in the US market since 2007. Our patients have likely heard far more about these devices through marketing, chat rooms, and word of mouth, than we as physicians have through the medical literature. Because ENDS are not currently regulated by the US Food and Drug Administration (FDA) as medical devices— recent court decisions, denied the agency the right to such oversight—manufacturers of ENDS have not been required to establish either safety or efficacy, and we have had few data with which to answer our patients’ queries about these products. Are e-cigarettes a smoking cessation tool? Are they a harmless alternative to cigarettes, as manufacturers claim?