Nasal blood flow is finely regulated by local release of neurotransmitters, neuropeptides and other bioactive molecules acting via paracrine mechanisms. We have investigated the effects of endothelin-1 (ET-1), a potent vasoconstrictor peptide, on the blood perfusion of rabbit nasal mucosa by laser Doppler flowmetry. After injection with ET-1, a potent and prolonged nasal vasoconstriction was observed. ET-immunoreactivity has previously been detected in nasal tissues and it is therefore suggested that ET-1 may participate in the regulation of nasal blood flow via paracrine mechanisms.