Nicolaus Copernicus (1473-1543), world-famous astronomer, born in Toruń, was also a Warmian canon (senior priest) and a physician to 4 consecutive prince-bishops of Warmia and of other Warmian canons. What medical conditions preoccupied Nicolaus Copernicus and whether they included kidney diseases can only be inferred from the extant prescriptions of Copernicus, as no record remains of any treatises by Copernicus regarding medicine. While no prescription penned by him is dated, several are traced to the period of his studies in Padua, Italy. The prescriptions indicate that he was concerned with conditions afflicting virtually all systems and organs of the human body including the kidneys. His personal library included at least 45 books, of which 14 dealt with medical issues. Copernicus used to write his prescriptions in the margins or on the blank pages of the treatises. They were mostly based on Avicenna's original prescriptions. The most common herbal ingredients used by Copernicus as remedies for symptoms of renal colic, hematuria and diuresis were common nettle (Urtica dioica), goosegrass (Galium aparine), rosemary (Rosmarinus officinalis), cubeb (Piper cubeba), common pumpkin (Cucurbita pepo), almond seeds and many others. It is hard to ascertain how effective the medical methods utilized by Copernicus may have been.