Today, changes in the condition of the hair are recognized markers of physiological and pathological processes for the clinician. The successes achieved have significantly expanded our knowledge of complex endocrine effects on hair, and also made it possible to establish that a wide range of metabolic and trophic disorders and some psychiatric diseases may for the first time be clinically manifested or accompanied by changes in density, properties, color and structure of hair. More than 300 genetic conditions are associated with hair pathologies, so the assessment of their condition is a simple initial diagnostic tool in pediatric dermatology and genetics. It is known from practice that patients often come to us with a complaint of a change in the condition of their hair, noticing only this symptom, which makes the trichologist both the primary link in medical care and a "medium" among related professions. That is, the degree of comorbidity of most trichopathologies requires the knowledge and experience of a competent clinician from a specialist practicing in the field of hair diseases. As a rule, a correctly diagnosed dermatotrichological disease helps to pay attention to the internal problems of the body in a timely manner.