The term “protection of legitimate expectations” in administrative law traditionally draws our attention to vertical relationships between the State and an individual. In my text I propose a non-traditional approach to the issue of protection of legitimate expectations in administrative law. Instead of analysing the problem from the perspective of the relationship between the administrative body and the individual, I have attempted to tackle the problem from the perspective of entities involved in peer relationships. The subject of my analysis is the principle of good faith as the axiological foundation for the protection of legitimate expectations in administrative law. Next the article addresses the specific legal institutions that express the protection of legitimate expectations in horizontal perspective: prohibition to make assertions contradictory to prior position (estoppel), institutions that express the protection of legitimate expectations in administrative contracts, as well as the principle of good faith in relationship between administrative bodies. The principle of good faith is a universal legal construct that forms the foundation of the legal system. Thus it is applicable in the sphere of administrative law, especially in the case of the relationship between equal-level entitiesa