Introduction. The article reveals the essence of the concept of «royalty», the analysis of existing methods of assessing royalties are their advantages and disadvantages. Since the method of determining the royalty rate, its objectivity and independence play a big role in the whole process of nature, as an instrument of change in the yield of the process. All this determines the relevance of the conducted research. Author of the problem complexity, the lack of input information, as well as large errors in the results of classical methods of assessment royalty rate, is proposed to solve it through the use of fuzzy inference. The aim of the article is theoretical development and practical implementation of the model estimating the royalty rate under the valuation of intellectual property in the use of natural resources. Methodology. The author builds a fuzzy model of the determination of royalty rates with a similar justification of the choice of linguistic variables based on correlation and regression analysis and the method of analysis of hierarchies. Also the author of the substantiation of the method of constructing a database of control rules. Result. The result of the practical application of the model developed by authors is presented in the example of determining the royalty rate in the extraction of raw materials in the construction industry (its size was 6,9%). This example serves as a basis for determining the error model, which is 13,8% (classic models are error 25–30%). Conclusion. It is shown that the use of fuzzy model allows more accurate (with no scope) to determine the royalty rate for a specific license agreements. The author emphasizes that the presented model is part of the model for evaluating intellectual property rights in the use of natural resources. Such models are used when evaluating cost approach and serve as a basis for determination of charges for use of natural resources (particularly fossil fuels), and damages arising during operation.