N-Arachidonoyl-L-serine (ARA-S), a recently isolated endocannabinoid with a distinct activity profile that diverges from typical endocannabinoids, does not interact with central cannabinoid (CB1), peripheral cannabinoid (CB2) receptors, or vanilloid receptor 1 (VR1). Unlike other compounds, ARA-S (5 mg/kg) counteracts the lowering of blood pressure induced by a 10 mg/kg intravenous bolus of abnormal cannabidiol (Abn-CBD) in anesthetized rat models. Additionally, akin to Abn-CBD, ARA-S induces relaxation in isolated rat mesenteric arteries and abdominal aorta and promotes phosphorylation of Akt and mitogen-activated protein kinase (MAPK) in human umbilical vein endothelial cells (HUVEC). The mechanisms through which ARA-S and Abn-CBD exert their effects on vascular systems show variations and merit deeper investigation.