Background: Chronic renal insufficiency (CRI) is known to be associated with coronary atherosclerosis and endothelial dysfunction. In this regard, higher incidence of coronary artery spasm (CAS) would be expected in patients (pts) with CRI. We investigated whether the CRI can be associated with clinically significant endothelial dysfunction.Methods: A total 830 consecutive pts without significant coronary artery disease underwent the acetylcholine (Ach) provocation test by injecting incremental doses of 20, 50, 100 ug into the left coronary artery were enrolled for the study. Significant CAS was defined as focal or diffuse severe transient luminal narrowing (>70%) with/without chest pain or ST-T change on ECG. The Ach provocation test results and its associated parameters were compared between the chronic renal insufficiency group (CRI,GFR<60mL/min/1.73m2 , n=72) and control group (n=758). Results The clinical and angiographic characteristics were similar between two groups except diabetes mellitus(18.1% vs 8.1%, p<0.01), hypertension (56.9% vs 38.2%, p<0.01) and peripheral artery disease (16.7% vs 5.1%) were more common in CRI group . After Ach injection, the rate of positive provocation test result was similar between the two groups. However, the rate of ischemic ST-T change and diffuse spasm were higher in chronic renal insufficiency group. Multivariate logistic analysis showed that CRI itself was not an independent predictor for Ach-induced diffuse CAS (odd ratio; 1.14, 95% confidence interval; 0.72-1.82, p=0.559) Conclusion: In our study, CRI was associated with higher incidence of ischemic ST-T change during the Ach provocation test and diffuse CAS, suggesting more profound and diffuse CAS can be occurred in pts with CRI. Special caution should be emphasized when a pt with CRI is presenting with typical or atypical chest pain.