Fasting for approximately 1 month is an obligatory practice for Muslims during the month of Ramadan. We attempted to evaluate the effect of the Ramadan fasting on the frequency of migraine attacks among observant Muslim migraine sufferers using a cohort cross-over study. Thirty-two observant Muslim migraine sufferers filled a migraine diary during the Ramadan month and the following month (control). Two patients failed to complete the fast because of migraine suffering. During the Ramadan month, the patient expressed 9.4 ± 4.3 migraine days in average (range 3-20) when compared with 3.7 ± 2.1 migraine days in average (range 1-10) during the control month (p < 0.001). This phenomenon was associated with longer duration of migraine, lower frequency of migraine attacks, and migraine with aura. It seemed to be less pronounced in patients experiencing throbbing headaches and in married patients. Previous prophylactic therapy did not dampen this. Physicians treating Muslim migraine patients should discuss potential Ramadan month exacerbation with their patients and provide counseling regarding the prevention of dehydration and caffeine withdrawal. Pharmacological prophylactic treatment should be considered.