That Ibn Sīnā’s “Canon of medicine” figures among the major classics of the history of medicine is doubted by no serious historian of medicine, eastern or western, Islamic or non-Islamic alike. It is therefore all the more surprising that so far no serious critical edition of this text was available. Certainly, a first, very timid step toward a really critical edition (published during the years 1982-1996) was made at the Institute of the History of Medicine and Medical Research (New Delhi), under the direction of Hakeem Abdul Hameed (1908-1999). It compared the four existing editions: Rome 1593; Būlāq (Cairo) 1877; Tehran (lithograph) 1878; and Lucknow 1905. In addition it used (a photocopy of) an ancient manuscript of Aya Sophia, dated 618, i. e. MS Aya Sophia 3686. With this new edition a further important step toward a full critical edition is made. Even if it is obvious that it does not yet present a “critical edition” in the full sense of the word, it has important merits.