OBJECTIVES: Cost-effectiveness of chronic diseases drug-therapy is estimated with the help of various pharmacoeconomic analysis methods. Cost-effectiveness analysis, cost minimization analysis, cost-utility analysis, cost-effectiveness analysis are used most often. We have proposed a modification of the cost-effectiveness analysis, which makes possible to record patient’s losses during treatment. Inflation coefficient K and its average value - Kmed may be more reliable tool in assessing the cost-effectiveness of treatment of recurrent disease.  METHODS: Formula evaluation of the effectiveness can be expressed as Kt ¨T DC(M/Nt), where k- coefficient of effectiveness of treatment at time t DC - amount invested in the treatment of one person M - number of patients in the beginning of treatment (original group) N – number of patients at the time T t – regular interval, running on the account (month, day, year, etc.) RESULTS: Analysis of the coefficient K shows a tendency to increase with an increase in DC price for the treatment or - on decreasing the number of patients N, remaining in the group. As the period t becomes longer entire formula is decreasing (inflation). The average coefficient k meaning is calculated according the formula Kmed ¨T ∑ Kt/t. Coefficient shows the average cost of one free of recurrence month in one patient from the group. The number of patients in group N decreases as a disease recurs, which leads to Kmed increase because of reallocating funds spent on chronic patients for the rest of patients. CONCLUSIONS: The study of economic efficiency through inflationary coefficient K, we have proposed, is a sensitive method for estimating treatment costs, and may prove to be a reliable tool for cost-effectiveness analysis of chronic patient drug therapy.