The article examines the phenomenon of disease. The author thinksthat this phenomenon is a complex system of many reasons with factors, influencing each other. That means that it is necessary toanalyze total combination of the person’s development conditions, theobjective social situation of development (L.S. Vygotsky), which putthe person into chronic somatic disease.The author has worked out and approved the concept of the diseasesituation. This concept includes: objective and subjective components.Objective component: the disease itself and its results – couldbe examined as an objective hard situation of living and it reflectsconditions of mental activities of the patient, psychological “cost” ofthe disease, the rate of loss of the former possibilities of the person.Subjective component supposes personal activity of the patient,sense of purpose, mechanism of self-control, first of all the standard of the person’s reasons and needs.