The writings of Hippocrates began to appear in print in the 1480s, and only a few of the works attributed to Hippocrates were printed in the 15th century. Though the date of this edition is unstated within the book itself, the ISTC ih00277500 attributes it to "about 1481", making it, and an edition of Hippocrates' De insomniis Ed: Andreas Brentius also attributed by ISTC ih00277000 to Rome: Oliverius Servius, "about 1481", possibly the earliest printed editions of any of Hippocrates's works. Digital edition of De insomniis from the Bayerische Staatsbibliothek at this link.