BACKGROUND The aim of this study was to evaluate the effect of blood-letting with wet cupping therapy (WCT) in migraine treatment and to determine whether there was any difference according to the phase of the moon when the treatment was applied. MATERIAL AND METHODS This self-controlled study was conducted in Karabuk between 2014 and 2016. Patients who were diagnosed with migraine were enrolled in the study. Migraine disability assessment questionnaire (MIDAS), demographic characteristics, migraine attack frequency and duration, and family history was used to assess the severity of headache. WCT was applied in 3 sessions and the questionnaire was administered before and 3 months after the final WCT session. Wilcoxon signed-rank test was used in pre-and posttreatment measurements, and the Chi-square test was used to check independence in two-way categorical tables. RESULTS A total of 85 patients were included. The reduction in MIDAS scores and number of migraine attacks was significantly greater in the WCT applications made in the first half of the month compared to those in the second half of the month. Although the reduction in visual analog scale (VAS) scores was greater in the second half of the month, it was also significant in the applications made in the first half of the month. CONCLUSIONS WCT was found to be an effective treatment of migraine. The effect on MIDAS, VAS, and the number of attacks was significantly better when the application was made in the second half of the month compared to those made in the first half.