In a study carried-out in double-blind fashion it was possible to demonstrate that skin vasoconstriction induced by cigarette smoking in normal volunteers is due to a concomitant enhancement of arginine vasopressin release. The skin blood flow reduction occurring after smoking was indeed more pronounced in the subjects reaching the highest levels of arginine vasopressin and this effect was curtailed by the administration of a specific vasopressin antagonist acting at the vascular site.