There is no doubt about the extensive medical knowledge of Cervantes at his time and some biographers affirm that he was a physician. Probably, part of this knowledge was the legacy of his father, a barber and surgeon, that bequeathed to him several medical books. However, there is an almost absolute ignorance related to his ailments and the cause of his death. Apart from a possible malaria, some authors have diagnosed him liver cirrhosis and diabetes mellitus, taking in account the Cervantes's own testimony, with hydropsy and uncontrollable thirst as important findings. However, some others explanations like heart failure are possible and certain data suggest terminal renal failure as his last illness.