ENThe main reason for convening the Parliament of 1646 was Władysław IV‘s desire to obtain consent for his plans for a war with the Crimean Khanate and the Ottoman Porte. The writs to the regional assemblies contained arguments intended to arouse in the nobility a sense of threat from the Khan and the Sultan. Nobility, however, was not favourable of the monarch‘s plans. Nevertheless, it is worth noting that the nobility mostly did not negate the need to defend the borders, and their representatives were to present certain concepts regarding the security of the Commonwealth during the Sejm’s session. It should also be emphasized that the attitude of the nobility towards the Tatar issue was not uniform. In most cases, the regional assemblies blamed resident senators and foreigners staying at court for the current state of the state. The deputies were supposed to show due respect towards the monarch, but they were instructed to express concerns about the compliance with the constitutional laws of the Polish-Lithuanian state. Keywords: Sejm, nobility assemblies, Wladyslaw IV Vasa, Polish-Lithuanian Commonwealth in 1st half of 17th century, Polish-turkish relations.