 Hernández studied medicine and botany at the University of Alcalá and may have traveled between cities in Spain, as it was common among physicians seeking to make a name for themselves.Moving from Seville with his wife and children, Hernández served briefly in the Hospital y Monasterio de Guadalupe and then at the Hospital Mendoza in Toledo, where he gained prominence for his studies of medicinal botany and publication of a Castilian translation of a work on natural history by Pliny the Elder.In 1567 Hernández became a personal physician to King Philip II.