The essence of dollarization phenomenon is considered in this paper. It is noted that dollarization occurs when the national currency does not completely perform the functions of money. In this case, the national currency is replaced in some transactions by foreign ones. Basically, it is the currency of highly developed countries with sustainable economic development. The defined main causes of dollarization in Ukraine are as follows: depositors attempt to keep their savings from devaluation result in financial crises accompanied by significant devaluation and inflation; distrust in regulator and government actions. The disadvantages of dollarization phenomenon for the national economy development are systematized and the following key ones are identified: decrease in the efficiency of NBU monetary policy, decrease in confidence in the national currency and banking system, decrease in demand for the national currency, growth of shadow economy and as the result tax revenues reduction. It is emphasized that one of dollarization types is financial dollarization, for which level assessment a number of indicators are selected: dollarization of loan and deposit portfolios, dollarization of MQ monetary aggregate. The structure of the deposit portfolio of individuals and legal entities in terms of currencies is considered and it is found that in periods of intensification of the crisis the level of dollarization increased, and in periods of relative stability – decreased. It is generalized that about 40% of the deposit portfolio is denominated in foreign currency. It means that consumers of financial services trust and save more in foreign currency. The structure of the deposit portfolio of individuals and legal entities in terms of currencies is considered and it is found that during the periods of crisis phenomena intensification the dollarization level increases, and during the periods of relative stability – decreases. It is summarized that about 40% of the deposit portfolio is denominated in foreign currency, i.e. the consumers of financial services trust and save more in foreign currency. The structure of the loan portfolio is analyzed and it is determined that the level of dollarization of the loan portfolio of legal entities is more than 40%, and consumer loans in foreign currency are prohibited, so the dollarization of the loan portfolio of individuals decreases annually up to 18%. The ratio of foreign currency deposits to money supply (MQ) is calculated, which, like other calculated indicators, proves that Ukraine has high dollarization level. Based on the carried out analysis, the conclusions concerning the need to coordinate the efforts of the central bank, government, parliament in order to reduce the dollarization level up to the natural level for the elimination of threatening consequences for the national economy are substantiated.