ENThe review article discusses a book edited by Leszek A. Wierzbicki and Dariusz Kupisz about the chronology of the Polish-Lithuanian Sejms (1569–1793). The polemic focuses on the chronology of the Sejms during the reign of Sigismund III (1587–1632). Keywors: Polish-Lithunian Sejm (1569–1793), Commonwealth of Two Nations, 16th and 17th centuries, Sigismund III (1587–1632).