The cyclical nature of economic crises, the essence of the economic cycle has been disclosed in the article, phases of cycle development have been characterized, the main reasons for cycle reproduction have been defined. The article is aimed to study the theoretical aspects of cyclical nature of economic crisis, the main phases of the cycle and the reasons for cycle reproduction. The method of retrospective historical analysis for a comprehensive study of the cyclical nature of economic crisis. The feasibility of different approaches to determining the internal and external causes of cyclical nature of economic development has been proved at the theoretical level. It has been determined that the economic cycle is periodic fluctuations in business activity, alternating rise and fall of market activity for several years. It has been substantiated that economic cycles can differ from each other in duration and intensity, but they all have one and the same phase. Scientific novelty of the results lies in distinguishing within the economic cycle of the country’s economy development for the 1996-2014 more short-term periods and substantiation the reasons and factors of cyclical fluctuations within them. The practical significance of the research lies in substantiation the nature and causes of cyclical nature of economic crises, in confirmation of their periodicity and frequency in the economy of Ukraine, in defining the relationship between the dynamics of economic conditions and dynamics of production and consumption of goods and services (retail trade dynamics). Particular attention is paid to the reasons for the economic cycle, the study of the dynamics of nominal and real GDP, industrial production, changes in the level of wages, and so on. The reasons of cyclical nature of economic crises have been grounded according with the results of the research. It is proved that the deepening economic imbalances significantly weakened macroeconomic stability, which ultimately led to the collapse of Ukraine's economy including as a result of foreign aggression. Further research will be aimed to the determination of cause-effect relationships and substantiation of the main factors of recurrence of Economy of Ukraine.