In the Campi Flegrei area of Campania, a region of Southern Italy, some thermal baths still exist, known for the therapeutical properties of their waters. Utilized since remote ages for the treatment of a variety of pathologies. In "De Balneis Terrae Laboris", an Italian poet of the Middle Ages and scientist, Pietro Anzolino da Eboli, reports every detail about more than thirty different thermal sites in the Campi Flegrei, including all therapeutic effects of their waters. Based on Pietro's manuscript, we report in the current paper all the sites whose waters were - among other indications - also recommended for the treatment of some urinary diseases.