ENThe concepts of trade secret as well as notaries' and attorneys' professional secrecy are analysed in the article along with regulation of these institutes in the Lithuanian legislation. Not only do the authors review the legal acts governing these questions, but also analyse the relevant case law (especially when it comes to the concept and main features of a trade secret). The authors further reveal the importance of the professional secrecy requirements in the work of notaries and attorneys to effective judicial protection and comprehensive legal counselling, as well as trust-based relationship between the clients and their notaries or attorneys. A significant part of the article is also dedicated to the review of the professional secrecy requirements in the work of notaries and attorneys. The authors analyse the roots of the legal privilege stemming from the Constitution, the significance of legal privilege to effective implementation of the right to judicial protection as well as enforcement of other rights of private persons. The existing doctrine of the Constitutional Court is also considered and reviewed in the article. When attorneys' professional secrecy requirements are analysed, the emphasis is put on its importance in the criminal proceedings.