The capsaicin analogue olvanil stimulated an increase in cutaneous blood flow when injected intradermally into the anaesthetised rabbit, as measured using a 133Xenon clearance method. Olvanil was found to be a 10-fold more potent vasodilator (on a molar basis) than capsaicin. The effect of both vasodilators was significantly inhibited by the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP-(8-37). These findings suggest that olvanil stimulates the efferent function of cutaneous sensory nerves in a more potent manner than capsaicin. We therefore suggest that olvanil is a useful pharmacological tool for studying the activity of neuropeptides released from sensory nerves.