The aim of this article is to present Polish-Moldavian relations in the years 1551-1572. This period, which almost fully overlapped with the reign of Sigismund II Augustus, was characterized by a considerable dynamism of relations between Poland and Moldavia. It also constituted a prelude to increased activities of Polish-Lithuanian magnates of this region - especially at the end of the XVI and in the two first decades of the XVII century. An interest in the region was caused by cultural and historical relations (going back to the medieval period) as well as the ambition and the reasons of State, which were perceived through the prism of personal interests. Analyzing some chosen issues, one may indicate two periods in the mutual relations of Poland and Moldavia. The years 1551-1563 are characterized by frequent actions of Polish- Lithuanian magnates on behalf of anti-Turkish pretenders to the throne or on their own behalf, without Sigismund II Augustus's consent. Those efforts were also supported by the Habsburgs, who aimed at the deterioration of Polish-Turkish relations. Sigismund II Augustus made attempts to oppose these actions, making conciliatory gestures towards Istanbul. It is worth mentioning that each hospodar on the Moldavian throne in that period was bound to turn to Turkey to save his rule. The second period, comprising the years 1563-1572, is different, due to the attitude of Sigismund II Augustus, who rejected passive policy and tried, mainly through diplomatic efforts, to gain influence on the choice of a hospodar. Periods of the rule of Aleksander Lapusneau and his son - Bogdan, resulted from Sigismund II Augustus' effective efforts. In 1572, on the king's inspiration, a subsequent Polish intervention took place to support the abolished hospodar - Bogdan. Military and diplomatic activities were undertaken simultaneously. Because of the strong Turkish-Tatar support, the undertaking turned out to be a failure. The situation was additionally complicated by the death of Sigismund II Augustus.