In graduate thesis on the topic „Retention of the title – obligations law aspects in commercial contracts“ analyzes the institute of retention of the title through six units, with special reference to the general terms of business of leasing companies, as one of the fundamental sources of commercial law in general, and especially as sources of law in which the clause the retention of the title finds its place. The work begins with the definition of the basic characteristics of the institute of the retention of the title, through its historical development and current arrangement; on the territory of the Republic of Croatia and within the European Union, the basic assumptions of the institute are also mentioned from the aspect of private international law. The work continues with the treatment of terms that represent the basis of the understanding of commercial law, and through the indication of the source of commercial law, a typology of commercial contracts, mentioning the ICC Model International Sale Contract, as an example of a type contract. Furthermore, special reference is made to the general terms of business themselves. In the fifth part, the work is focused on leasing, comparing it with the sale of goods contract, setting the basic assumptions of both operational and financial leasing, and finally analyzing the general business terms of leasing companies, with a special emphasis on the retention of title clause. In conclusion, the author presents the results of the entire research.