Abstract—Disturbances in the regulation of cytosolic calcium (Ca²⁺) concentration play a key role in the vascular dysfunction associated with arterial hypertension. Stromal interaction molecules (STIMs) and Orai proteins represent a novel mechanism to control store-operated Ca²⁺ entry. Although STIMs act as Ca²⁺ sensors for the intracellular Ca²⁺ stores, Orai is the putative pore-forming component of Ca²⁺ release–activated Ca²⁺ channels at the plasma membrane. We hypothesized that augmented activation of Ca²⁺ release–activated Ca²⁺/Orai-1, through enhanced activity of STIM-1, plays a role in increased basal tonus and vascular reactivity in hypertensive animals. Endothelium-denuded aortic rings from Wistar-Kyoto and stroke-prone spontaneously hypertensive rats were used to evaluate contractions because of Ca²⁺ influx. Depletion of intracellular Ca²⁺ stores, which induces Ca²⁺ release–activated Ca²⁺ activation, was performed by placing arteries in Ca²⁺ free-EGTA buffer. The addition of the Ca²⁺ regular buffer produced greater contractions in aortas from stroke-prone spontaneously hypertensive rats versus Wistar-Kyoto rats. Thapsigargin (10 µmol/L), an inhibitor of the sarcoplasmic reticulum Ca²⁺ ATPase, further increased these contractions, especially in stroke-prone spontaneously hypertensive rat aorta. Addition of the Ca²⁺ release–activated Ca²⁺ channel inhibitors 2-aminoethoxydiphenyl borate (100 µmol/L) or gadolinium (100 µmol/L), as well as neutralizing antibodies to STIM-1 or Orai-1, abolished thapsigargin-increased contraction and the differences in spontaneous tone between the groups. Expression of Orai-1 and STIM-1 proteins was increased in aorta from stroke-prone spontaneously hypertensive rats when compared with Wistar-Kyoto rats. These results support the hypothesis that both Orai-1 and STIM-1 contribute to abnormal vascular function in hypertension. Augmented activation of STIM-1/Orai-1 may represent the mechanism that leads to impaired control of intracellular Ca²⁺ levels in hypertension.