The aim of this master's thesis is to get familiar with the legal institute of ownership claims. The ownership lawsuit is an institute of the real right, that is the subjective right arising from the right of ownership or its violation. As the legal foundation of a property claim is the right of ownership (proven, or at least envisaged), the person who applies this claim, the thesis also deals with property, as one of the most important institutions of legal order, its concept and characteristics. Moreover, the acquisition of ownership rights is being explaind. The protection of property rights, as an objective to be achieved by proprietary lawsuits, and is therefore related to them, is dealt with in general, with the processing of the claim itself and its comparison with similar requirements. Ownership lawsuits, as the central term of this thesis, are processed firstly by types, secondly each type in general and through the prism of active and passive legitimacy and finally the very lawsuit itself. This thesis consists of a very important, comprehensive and complex matter, whose understanding requires the foreknowledge of basic civil law institutes, which is explained briefly in the work before the processing of the ownership lawsuits. For it is, in fact, an institute that is one of the most important pillars and foundations of the civil law design, so it is a topic that is extensive and inexhaustible. However, the thesis provides a good insight into the fundamental features of this legal institute.