The purpose of the article is to consider the form and contents of a letter from Isabella of Aragon, Duchess of Milan and of Bari, and the circumstances in which it was written, as well as to print its text. The letter, which survives in Cambridge University Library, is autograph, written in Italian and dates from 2 September 1501. It alludes to various misfortunes that had befallen Isabella. It asks its addressee, Ferdinand the Catholic, the conqueror of the kingdom of Naples, to confirm her in possession of the duchy of Bari and her lands in Calabria, a request that was successful. The letter is compared with other letters of Isabella and with letters of other female members of the Aragonese house of Naples.