The article explores the roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) in the cutaneous vascular and sweating responses to intradermal administration of adenosine triphosphate (ATP) and the contribution of adenosine to ATP-induced skin vasodilatation. Topics discussed include the association of heat stress-induced hyperthermia with increases in intravascular ATP and the physiological relevance of interstitial ATP on thermal hyperaemia.