After the conversion of Lithuania, Christian norms changed the old pagan traditions in society by adapting them to local customs. Although the blending of Christianity with old traditions in the Grand Duchy of Lithuania (GDL) has already been studied by historians, previous research has not provided a clear picture of how it changed the institution of marriage. Marriage in the GDL has usually been studied based on an analysis of the institutions of matrimonial property (dowry, dower). This article focuses on the institution of marriage and the concept of the validity of marriage in the 16th-century GDL. The author investigates the secular laws of the GDL, which, despite being codified in the Statutes of Lithuania, preserved some local eleme...