Background: Endothelial dysfunction is an important component of hypertension which has been well described. However, whether hypertension is an independent risk factor of coronary artery spasm (CAS), which is characterized by significant endothelial dysfunction, is still uncertain. Method: We performed selective intracoronary provocation tests with incremental doses of in 514 hypertensive patients (pts) and 675 non-hypertensive pts from November 2004 to June 2007. Acetylcholine (Ach) was injected by incremental doses of 20mg (A1), 50mg (A2) and 100 mg (A3) into the left coronary artery. Significant CAS was defined as transient >75% luminal narrowing. Result: Baseline characteristics were similar between the two groups. Although the incidence of CAS in baseline angiography were not different, hypertension group had a significantly higher positive provocation test rate (65.8% vs 54.8%, P<0.05) with lower dose of Ach than those of non-hypertension group. Hypertension pts also had higher rates of fixed lesion in spasm segment and myocardial bridge (MB) than those of non-hypertension pts (Table). The incidence of chest pain, EKG changes, spasm type (focal or diffuse) and multivessel involvement were not different between the two groups. However, the multivariate logistic analysis showed that hypertension was not an independent risk factor of significant CAS. Conclusion: Although hypertension pts had higher incidence of positive provocation test with lower Ach dose, hypertension itself was not an independent risk factor of significant CAS. Interestingly, hypertensive pts had more fixed lesion (possible mixed angina) and MB and should be translated into clinical practice.