The author considers the activity of agency in the sale and lease of real property and the mandatory insurance of agents. This activity was introduced into the legal system of the Republic of Serbia for the first time under the Law on Agency in Real Property Sales and Lease (ZOP). The new activity was perfected within the legal system by introducing changes in the requirements for registration in the Register of Agents. The improvement of the activity lasted from November 2013, when the ZOP was adopted, until January 2020, when the last amendment to the ZOP began to be applied. One of the stipulated requirements for registration into the Register of Agents provided for the submission of a valid insurance contract concluded in accordance with Article 13 of the Law on Agency in Real Property Sales and Lease. By making a connection between the provisions of the ZOP on mandatory insurance and the Official Explication under Law on Agency in Real Property Sales and Lease, the author established that the provisions of the Law did not give a clear answer to an agent whether he had to renew a valid insurance contract after having done the registration. The author tries to overcome the stated ambiguity of the provisions of the Law on Agency in Real Property Sales and Lease by proposing, in the conclusions, a wording that corresponds to the comparative legal solutions on the mandatory insurance of property sales and lease agents.