A non‐peptide neurokinin1 (NK1) receptor antagonist, RP 67580, that is selective for the rodent subtype of the NK1 receptor, dose‐dependently reduced plasma extravasation in the dura mater produced by electrical stimulation of the trigeminal ganglion in rats, with an ID50 of 0.6 μg kg−1. Its enantiomer RP 68651 was some 400 fold less active. The results indicate that neurogenic plasma extravasation within the dura mater is NK1 receptor‐mediated and suggest that NK1 receptor antagonists may have a role as antimigraine agents.