Chronic migraine (CM) is the most prevalent disabling primary daily headache disorder, the prevalence of  CM in Russia is 3 times as much as worldwide (6,8% vs 2% respectively). The diagnosis of CM is based on the International Classification of Headache Disorders 3rd edition (beta-version) dated 2013. (ICHD-III). Not all the physicians are fully aware and/or actively use the diagnostic criteria stated in the ICHD-III. Underdiagnosis of CM causes the inadequate treatment that is still the problem for both GPs and neurologists. This article reviews in detail the specific principles of clinical interview that is critically important to evaluate the status of the patient. The use of special clinical scales, questionnaires, diaries helps to diagnose CM and other co-morbid mental and somatic disorders, to evaluate disability and decreased migraine related quality of life. The interpretation of the findings remains the most important point to diagnose CM, to define the need of additional exams and to evaluate the efficacy of therapy.