Migraine without aura (MWA) is a clinical condition characterized by multiple immune deficits, which may play an important role in the pathogenesis of the disease. In this respect, previous studies have demonstrated that patients with MWA exhibit profound dysfunctions of phagocytosis and killing exerted by polymorphonuclear cells (PMN) and monocytes. This may correlate with the increased frequency of infectious processes observed in these patients. The overall results suggested to evaluate the presence of circulating cytokines (CKs) in subjects affected by MWA. In particular, the present data point out an exaggerated spontaneous release of tumor necrosis factor (TNF)-alpha in a group of MWA individuals, which correlates with detectable levels of bacterial lipopolysaccharides (LPS) in their plasma. In view of the different biological activities displayed by TNF-alpha in the host, such as effects on the nervous and vascular systems, hemodynamics modifications and demyelinating properties, the intervention of this CK in the pathogenesis of MWA will be discussed.