It is well known that some migraine patients recognize the change of their migraine characteristics over time. These patients often complain chronic daily headaches instead of episodic attacks of migraine. Such chronic headaches are resistant to medication, and called refractory or intractable migraine. Refractory migraine is a term, which has been used for many years, but until recently, there has been little attention paid to its definition. The criteria used for diagnosis of refractory migraine have varied considerably. In most circumstances, however, the definition has included a poor response to "standard" preventive medications. This review article introduces the proposed criteria for definition of refractory migraine and the therapeutic strategies against refractory migraine.