The manner of use of the land let into perpetual usufruct is specified not only the by the legal provisions or the principles of social coexistence, but also by an agreement or a decision conferring this right. If letting land for perpetual usufruct is aimed at erecting building structures or other equipment, the agreement should also specify the date of the commencement and the completion of the works.The State Treasury and local government units are required to control the manner of use of the real estate let into perpetual usufruct, and to take appropriate action in the case the real property is used in the manner inconsistent with this agreement or decision. The main issue is to determine the intended purpose of perpetual usufruct, which is difficult in practice, especially in the cases where perpetual usufruct was not established by way of an agreement, but by enfranchisement decisions issued in the years 1990-1997.The aim of the study is to analyze the effects of change in the manner of use of real estate by perpetual user. These issues, in practice, raise numerous doubts about the rules of proper conduct as well as the consequences for perpetual users. The emerging interpretation ambiguities ...