Introduction. Due to the necessity to obtain the reliable results of a clinical trial and to distribute it to the general population of patients the problem of recruiting the adequate number of individuals to participate in the study as objects of observation in the group receiving the investigational medicinal product or as a member of the control group should to be solved. Aim of study. The aim of our study was to research and to justify practically the methodological approaches to determining financial compensation for participation of volunteers in the clinical trials and the appropriate methods of its calculation. Material and methods. For the purpose of determining the baseline factors for calculating the hourly compensation the survey of healthy volunteers and of expert professionals as well as the analysis of its results have been done. Questioning healthy volunteers regarding their attitudes towards inconvenience and discomfort during participation in clinical trials was held at the Ukrainian clinical research centers. Survey participants number was 99, they were healthy volunteers who took part in the first phase clinical trial or bioequivalence studies. The expert survey included questioning of the 193 professionals from Ukrainian clinical research centers, CRO, pharmaceutical manufacturers – research sponsors and collaborators State Expert Center Ministry of Health of Ukraine, who were involved in the planning, organization, implementation and evaluation of clinical trials as well as their regulatory control. Results of study. Using the method of pairwise comparisons and iterative refinement procedures the collective estimate of experts questionnaire results has been performed, by the results of which the nine indicators have been identified and the importance of each of them as units of discomfort have been established. Motivational factors of voluntary participation in clinical trials have been studied. Motivation system for participation in clinical trials by patients and healthy volunteers has been rationalized, whereas methods of calculating monetary compensation for such participation have been suggested. The two methods of calculating of the financial compensation were proposed: first - hourly compensation for the time which was spent on clinical trials, the second - hourly-bonus compensation for the possible discomfort and inconvenience of participation in clinical trials in accordance with the ethical rules for research involving people as objects of observation. Conclusion. Achievement of the organizational and financial constituent ensuring participation of volunteers in a clinical trial on the one hand should assure the appropriate experimental foundation for reliable research conducting and on other hand should focus attention on the fulfillment of mental and ethical rules for investigations involving human as a studied object. Basing on the results of an analysis and the survey performed which involved qualified experts regarding aspects affecting volunteers enrollment in a clinical trial, the scientifically substantiated system of the volunteers discomfort and inconvenience assessment in a clinical trial has been proposed, which includes criteria: study duration, adverse events/adverse reactions possibility, blood sampling during study, discomfort caused by study design, inconvenience to participate in a clinical trial. Two techniques for calculation of the financial compensation for healthy volunteers participation in a clinical trial have been proposed: the first one is the payment by the hour spent for participation in a study, and the second one is the hourly pay with bonus for possible discomfort caused by involvement in a clinical trial. In the further study authors plan to research the aspects of risk assessment associated with volunteers participation in a clinical trial and its considering as an additional constituent in the process of the calculation of financial incentives to participate in a clinical trial.