Since we live in the times when the validity of laws is often challenged, either because of the restrictions which the laws impose on individuals or because they stand in the way of political or other desirable general objectives, the impact of natural (canon) law on positive law needs to be examined, all the more so because marriage is the foundation of the family and the family is the basis of every national and state life and affects the social and public character. In the wake of the adoption of the Civil Code, which will legally transform the identity of Serbian legislature, it is important to review the way in which certain legal solutions were made. The impact of canon law on marriage regulations in Medieval Serbia can be traced back to Saint Sava’s (Nemanic) Nomocanon (Book of Kormchy), with a special reference to the legislature of Emperor Stefan Dusan Nemanic. This paper will therefore point to the legal and historical basis for such a review of regulations in the future Civil Code of the Republic of Serbia.