 Gómez Pereira’s biography is largely unknown. Only a few data have been extracted from the Prologues of his books and from some legal documents discovered in his hometown Medina del Campo (Alonso Cortés 1914: 10; González Vila 1976: 95–96). He was a prestigious doctor who practiced his profession in his own town, which at that time enjoyed great prosperity as a center of commerce. His medical reputation may have gone beyond the limits of Medina del Campo since he was summoned by the court of Madrid to look after the health of the Infante, the future Charles II, son of Philip II. The origin of his family is uncertain (the surname “Pereira” indicates that its origin was probably in Galicia or Portugal). It seems that his family was in trade and had a favorable position. Because of this professional activity it has been suggested that Gómez Pereira came from a family of Jewish “conversos” (González Vila 1976: 96–97; Rodríguez Pardo 2008: 195–199).