In 23 patients with common migraine (CM), immune responsiveness and frequency of immunocompetent cells were investigated. In particular, phagocytosis and killing of Candida albicans by polymorphs (PMNs) and monocytes were analyzed. Also, the percentages of CD3+, CD4+, CD8+, natural killer, and CD15+ cells were evaluated by direct immunofluorescence using specific monoclonal antibodies. The results showed deficits of phagocytosis or killing exhibited by PMNs and monocytes. These immunological findings are discussed in terms of perturbation of immune status in CM patients during migraine attacks.