Following upon a careful selection of eight contemporary books, identified according to specific criteria as books of medical instruction, a semiotic cross-comparison was undertaken between one group, consisting of three textbooks of medicine and intended for professional readers, and a second group, consisting of five popular home medical books and addressed to the layman. Preliminary research showed that all of the selected books, whose titles will appear at the end of this paper, enjoy wide dissemination in North America. The books were compared not only in terms of their linguistic and semantic properties, but also in terms of some of the historical, social, and critical contexts to which they belong. As anticipated, explicit differences could be demonstrated both on the levels of style as well as of contents.