This article is about the prediction of bankruptcy of companies in Poland. The author compares two methods of forecasting the risks of bankruptcy of companies: artificial neural networks and fuzzy logic. In the conducted research he used data of 185 companies listed on the Warsaw Stock Exchange. This population of firms was divided into learning and testing set data. Each company has been analyzed using the absolute values of 14 financial ratios and the dynamics of change of these ratios. The author's developed models of fuzzy logic are characterized by high efficiency. These studies are the first attempt to use fuzzy logic to predict the bankruptcy of companies in Poland and one of the first in the world. Obtained results demonstrate the great potential of this method.