Chronic migraine (CM) is defined as headache occurring on 15 or more days per month for more than three months, which, on at least 8 days per month, has the features of migraine headache. In the International Classification of Headache Disorders, CM is defined as a separate entity and the presence of drug overuse headache is removed from being an exclusion criterion. CM accounts for more than 10% of all migraine patients and includes the group with the most prominent disease-related disability. Diagnosis is often overlooked and most patients do not receive appropriate treatment. CM is associated with social and economic burdens such as frequent use of health services, drug overuse, and significant disruption to work and school life. Compared with episodic migraine, more frequent comorbid disorders are important in migraine chronicity, treatment, and course. With appropriate treatment in CM, it is possible to increase the quality of life of the patient and to reduce the social economic burden associated with migraine. In this review, the disease burden of CM, accompanying comorbid diseases, and current treatment options are reviewed.