Medicine and astronomy were both scientific disciplines to which visual demonstration proved helpful, were taught in the universities, and were deeply influenced by humanism and by the development of print culture, but they did not use printed images in the same way. Thus, all the aspects of astronomical activity benefited from the accompaniment of printed images, whereas, even for anatomy, illustration does not seem to have been seen as a necessity in Renaissance medical books. To explore such a difference, the (...) chronology of the development of illustration in both fields (from the first illustrated incunabula to the mid-sixteenth century) is compared, and some explanations (economical, epistemological, cultural) are proposed and questioned. -/- . (shrink)