Having in mind the history of the postal service it may be concluded that a special role has been played by the Postal Law, through which it is possible to follow the development of relations between the state power and the postal service. Since the first legislative norm was issued by Ferdinand I in 1535, the Postal Law in Hungaria, an so as well in Slovakia, could have been characterised as the royal law. Thus the finance gained by the postal service belonged to the royal treasury. Simultaneously the Postal Law documents social and political conditions in respective period, and serves as an indicator of social-political events in Hungaria. By modification of postal regulations the sovereigns reacted to economic and social life in the country. Thus 250 years ago Maria Theresa, influenced by reform efforts, introduced several changes in the field of postal transportation, of which predominantly The Postal Act No. 31 of 1741, The Postal Order of 1743, and The Postal Patent of 1748 should by mentioned. The research of the Postal Law is also covered by Slovenská pošta, š. p., The Museum of Postal service, established on March 1. 2000 in Banska Bystrica.