Introduction. The outbreak of a new koronavirusny infection put before society unique, economic and ethical problems as it imposed new requirements to social systems first of all – to health care systems, both on national, and at the global level, including concerning differentiation of categories "disease" and "health". At the same time, still there are no uniform and reliable approaches to assessment of both personal, and population health allowing to improve it, including encouraging healthy behavior. The lack of real data on prevalence of diseases among the population, about number of sick people, reduces effective management of the industry as significantly complicates a specification of the purposes and tasks, narrows possibilities of reduction of unnecessary costs of rendering medical services with doubtful usefulness. Research objective. Studying of modern aspects and problems of assessment of individual and public health. Materials and methods. The content analysis methods, information and analytical materials of the Russian and foreign authors, materials of monographic researches including placed on the Internet are used. Results. Indicators of the general and primary incidence reflect number of cases of registration of a disease (not sick people) considered on the basis of negotiability of the population to the state medical organizations, but not the number of sick people in society in the Russian Federation. The existing accounting also does not include cases which could be revealed when performing routine inspections and cases of the hospitalized incidence. Including for this reason in Russia the long time exists a paradox at which the hospitalized incidence of a myocardial infarction is higher than the general incidence. Discussions. WHO defined health as "a condition of full physical, spiritual and social wellbeing, and not just absence of a disease or other defects". For the practical doctor such definition of WHO is abstract according to which the human health is rather an exception, than the rule. The doctor (and even the team of doctors of several specialties) will not be able to define the person is healthy or is sick as medical education provides training in methods and skills of recognition of diseases, to methods of their treatment, but does not provide training in methods of assessment of spiritual and social wellbeing of the person. The illegibility of borders between health and a disease has a strong impact on behavior of doctors who can diagnose this or that disease, but cannot define the person is healthy or is sick in general. As a result the medicine began to develop in the course the client - the focused approach which, despite its attractive social sense, pays attention only to formal characteristics and desires of the patient. Conclusions. Uncertainty of borders between health and a disease represents the serious unresolved problem influencing relationship of medicine and society, is one of the reasons of growth of expenses on medical care in the modern world, leads a health care system to loss of the basic appointment. The most realistic assessment of prevalence of these or those diseases among the population can be given on the basis of studying of results of selective cohort researches and also the personified registers of the persons who asked for medical care