The sources available for the reconstruction of the exciting developments that took place in Greek medical thought and practice in the late fifth and fourth centuries B.C. are extensive, although in places defective and in places biased. They fall into three main categories, first the extant treatises of the Hippocratic Corpus, second other literary sources, and third the inscriptional evidence, and a summary analysis of each in turn will serve to illustrate both the range and the limitations of the information they provide.

The great majority of the sixty or so treatises in the so-called Hippocratic Corpus date from the later part of the fifth or from the fourth century. The main exceptions are a handful of works, such as On Nutriment, On Sevens and some of the treatises on medical ethics, that show Stoic or Epicurean influence, and one, On the Heart, that is generally thought to be approximately contemporary with the work of the Alexandrian biologists Herophilus and Erasistratus. Even when we discount these few later works, the variety within the Hippocratic Corpus is very great, and the treatises – all of them anonymous – are evidently the work of many different authors representing, in some cases, radically divergent shades of opinion. Whether Hippocrates himself was responsible for any of them is controversial. Although Hippocrates is occasionally referred to in contemporary or near contemporary writers, notably Plato, Aristotle and Aristotle's pupil Meno, the medical historian whose work is excerpted in the papyrus Anonymus Londinensis, they provide only very limited, and in places conflicting, evidence concerning the medical theories and practices he upheld, though they confirm the admiration and respect in which he was held already in the fourth century.