[Cristóbal de Vega (1510-1573), physician to prince Don Carlos (1545-1568)].

This paper represents biographical aspects concerning the always-delicate health of Prince Don Carlos (1545-1568), first-born son of the King Felipe II of Spain (1527-1598). The main conditions and circumstances of his pathobiography were drawn from interesting data offered by one of his royal doctors, the former professor of the University of Alcalá, Cristóbal de Vega (1510-1573), throughout his significant medical career. In particular, the report on the quartan fevers suffered by Don Carlos in Doctor Vega's Commentaria in librum Aphorismorum (1568), provides considerable and previously unknown clinical data on the disease.