The treatise was in origin a polemic against the Erasistrateans in Rome whom Galen found to be in opposition to his own views. It is of interest not only for Galen's views on venesection but also for the fragments of the writings of Erastistratus contained in it. The text has not yet appeared in a modern critical edition. The Kühn edition of 1826 is the most recent, but Kühn did not go beyond the work of the Renaissance editors in dealing with the numerous corruptions of the text. The emendations proposed below are occasioned by the want of a satisfactory reading anywhere in the tradition.