In non-industrialized countries, populations with the lowest literacy rates have the poorest health status. In the United States, however, there is no published research on whether illiteracy, independently of other sociodemographic factors, is related to health status. There are numerous plausible mechanisms by which such a relationship could occur. For example, published reports indicate that most information handouts, consent forms, and other materials for patients are written at reading levels too difficult for most American adults. These and other findings may have important implications in the health care of underserved populations. Research is needed to determine the health effects of impaired literacy skills among Americans, and to develop non-literacy-dependent methods for providing patient education, obtaining informed consent, and administering diagnostic tests.