We measured, by RIA methods, ictal and interictal levels of substance P (SP), calcitonin-gene related peptide (CGRP) and neurokinin A (NKA) in the plasma of 30 young migraine patients with aura (MPA) and 45 migraine patients without aura (MWA), and compared the results with those of 30 age-matched controls. There were no significant differences between the levels of these vasoactive peptides in the control group and the levels in both migraine groups studied in headache-free periods. An elevation of CGRP levels in plasma was found during attacks in MPA and, to a lesser extent, in MWA (p < 0.03 and p < 0.05, respectively). A significant increase in NKA levels was also demonstrated in the MPA and MWA groups (p < 0.02 and p < 0.04, respectively). These data suggest, although indirectly, that CGRP and NKA could be involved in the pathogenesis of migraine attacks in juvenile migraine patients.