The influence of medieval Italian medicine first reached Catalonia via Montpellier. Physicians from Salerno are known to have worked in Aragon, and many Italian medical and surgical texts circulated in Catalonia. By the end of the 15th century it was Valencia that maintained close ties with Italy, and in the 1st third of the 16th century, at the height of Renaissance humanism, the Castilian universities became the greatest Spanish patrons of medicine. PostVesalian anatomists were active and many Castilian doctors were educated in Italy. In both medieval and Renaissance Spain the most commonly described renal pathology was lithiasis. The works of Joanes Jacobi (14th century) and Julian Guttierez (15th century) are outstanding, and foreshadow the monograph on lithiasis by Sanchez de Oropesa (16th century) and the work of Francisco Diaz, probably the greatest Spanish contributor to modern nephrology. He devoted 3 books of his collected professional experience to lithiasis, renal ulcers and sores, kidney inflammation and other processes including haematuria. His view of renal anatomy was totally modern, and he strongly advocated autopsy as a means of determining the cause of death. This underlines the new anatomopathological approach to investigation that was adopted in Renaissance Spain.