This study aims to investigate the diagnostic performance of stress cardiac magnetic resonance (CMR) for evaluating low-and intermediate-risk patients with suspected acute coronary syndrome (ACS). Consecutive 51 patients (33 males, 17 females, mean age 58.7 +/- 9.6 years) with low-to intermediate-risk of disease for suspected ACS were prospectively enrolled in this study. Diagnostic performance of stress CMR was compared with single-photon emission computed tomography (SPECT) for diagnosis of ischemia with invasive coronary angiography as the reference method. The area under the receiver operating characteristic curve (AUC) was calculated and compared between these two imaging modalities. For detection of ACS in the low-risk populations, on a per-patient assessment, the AUC of CMR was 0.879, which was slightly superior to that of SPECT at 0.723 (p = 0.19, n = 22). On a per-vessel assessment, the AUC of CMR was 0.923, which was significantly higher than that of SPECT at 0.774 (p = 0.04, n = 66). For detection of ACS in intermediate-risk populations, there was no significant difference between CMR and SPECT on a per-patient and per-vessel assessment, with corresponding AUC being 0.885 and 0.900 for CMR and SPECT (p = 0.78, n = 29), 0.770 and 0.785 (p = 0.75, n = 87), respectively. Stress perfusion CMR has excellent diagnostic performance in both low-and intermediate-risk patients being evaluated for ACS. Compared with SPECT, stress perfusion CMR performed better in the low-risk populations.