(Title in Polish - 'Reguly pragmatyczne Jezyka Hasel Przedmiotowych Biblioteki Narodowej i Uniwersalnej Klasyfikacji Dziesietnej na przykladzie stosowania tych jezyków w 'Przewodniku Bibliograficznym') The authoress analyzes pragmatic principles of National Library of Poland Subject Headings (JHPBN) and Universal Decimal Classification (UDC) - two systems of broad application and long tradition, used in many Polish libraries and Polish national bibliography. The pragmatics of those systems is interesting for two reasons. First, they differ with regard to their vocabulary and structure, which offers the possibility of comparing their mutual impact. Second, both systems are not only used in the National Library of Poland, but also created (JHPBN) or adapted (UDC) by that institution. As a result of the analysis pragmatic principles of both systems have been isolated and discussed and four key reasons for their formulation have been presented.