The business community from Italian cities had an important role in the development and the prosperity of medieval Dubrovnik. One of the most distinguished foreigners in Dubrovnik was the pharmacist Monaldo Viganti whose activity, based on published and unpublished materials in the Dubrovnik Archives, shown in this -paper from 30-80s of the 15th century. In addition to running pharmacy, he especially excelled in managing loan services by financing -Dubrovnik cloth producers and merchants. Viganti was a full citizen of Dubrovnik and afterwards Antunini, he intensively traded on the Apenine Peninsula and inside the Balkans. He often did business associated with other merchants. After his arrival in Dubrovnik his closest collaborator was Paolo Tomazi, pharmacist married to Viganti's sister. Later he became a member of numerous trade associations. He started his family in Dubrovnik and his heirs kept on his tradition and became prominent pharmacists in Dubrovnik. Monaldo was a link, which contributed, the prosperity of Dubrovnik and through trade activities connected Apenine and Balkan Peninsula.