Objective. -The aim of the present research was to verify the levels of the soluble adhesion molecules sL-and sE-selectins, intercellular adhesion molecule (sICAM)-1, and vascular cell adhesion molecule-1 in serial samples of internal jugular venous blood taken from migraine patients without aura (MWoA) during attacks. The expression of leukocyte function antigen (LFA)-1 and very late activation antigen (VLA)-4 was also assessed on lymphocytes obtained from jugular venous blood. Levels of certain proinflammatory cytokines (tumor necrosis factor-α[TNF-α], interleukin-1β[IL-1β], IL-4, and IL6) were also determined and correlated with those of adhesion molecules. Patients and Methods. -Seven MWoA patients were admitted in the hospital during attacks and blood samples were taken immediately after catheter insertion, at 1, 2, and 4 hours after attack onset, and within 2 hours after its termination. The levels of adhesion molecules and cytokines were measured with ELISA method. The expression of LFA-1 and VLA-4 was assessed by flow cytometry. Results. -A parallel transient increase of sICAM-1, TNF-α, and IL-6 was observed in the first 2 hours after attack onset compared with the time of catheter insertion (P< .0001, < .001, and < .003, respectively). The proportion of CD4+and CD8+T-cells expressing high levels of LFA-1 showed instead a progressive down-regulation with significantly lower percentages at 2 and 4 hours after attack onset (P < .01 and < .022, respectively). No variation in the percentage of VLA-4 expressing cells was observed at any time of the study. Conclusions. -The transient increase in sICAM-1 and TNF-αfound in the internal jugular blood of MWoA patients assessed ictally can be induced by sensory neuropeptides released from activated trigeminal endings. The progressive decrease in sICAM-1 levels during attacks and the down-regulation of LFA-1 expression by lymphocytes could antagonize their transvascular migration, supporting the hypothesis of sterile inflammation in the dura mater during migraine attacks.