ENThe famous Italian reformer Pietro Paolo Vergerio (1498-1565) during his two trips to Lithuania, Poland and Prussia‘s Koenigsberg published a number of works important for the early period of the Reformation in this region, among which «Duae epistolae» (1556) occupies a special place. The publication contents the correspondence of the nuncio of Pope Luigi Lippomano with the ancestor of the Lithuanian Reformation Radziwill the Black (1515-1565), who here for the first time announced his conversion to the Protestant faith. Soon the translations of the two above-mentioned letters into German (1557) and Polish (1559) were published. The article analyzes the connections between Vergerio and Radziwill in a historical context, examines the content of the book and the main ideas of its main text, the answer of Radziwill to Lippomano.