This paper elaborates on rei vindicatio in Roman law with a comparison to its regulation in contemporary Croatian law. Following the introductory analysis of the right of ownership, which in practice is an imperative right of each person or legal entity enjoying full legal protection through various procedural means, this paper further focuses entirely on rei vindicatio (“vindication of property”) as a particularly important procedural means of protecting the right of ownership. Rei vindicatio was mentioned as early as in the Laws of the Twelve Tables, and was the most important claim of a quiritary, nonpossessory owner for the protection of his property rights. To succeed in a litigation, the plaintiff had to prove his right of ownership, the defendant's possession and the identity of the object in dispute. The proof method differed depending on the development of procedural actions. The plaintiff's main claim was aimed at surrendering the possession of the object in question, and secondary claims were related to compensation of benefits from the thing and compensation of damage due to the deterioration or destruction of the thing. At the same time, the defendant, as owner or detainer of the thing in dispute, could seek compensation for the costs he incurred on the things during his possession. The legal regulation of this legal action in Roman law has been a model for its regulation in modern Croatian law. This is apparent not only from the name of the legal action, which continues to be used in the Latin original or the adapted version in the Croatian language, but also from the method of protection of the right of ownership pursued by this legal action. However, the needs and possibilities of the times change and there is a clear distinction between this legal action then and now. This distinction is reflected not only in a broader concept of ownership, where the capacity to sue to the owner in indirect possession and a greater possibility to avoid the so-called diabolical proof (probatio diabolica) was instituted, but also in the fact that objections and counterclaims of the defendant represent separate procedural actions. The overview of the position of this action previously in Roman law and today in modern Croatian law demonstrates the influence of Roman law on modern legal systems, especially its influence in the area of the law of property.