Objective To evaluate the ability of 64-slice spiral CT(64-MSCT) in demonstrating the coronary collateral circulation(CCC).Methods Patients undergoing 64- MSCT coronary angiography with relatively good image quality from August 2005 to April 2007 were entered into the study according to following requirements: patients underwent a traditional coronary artery angiography (CAG) after the coronary CT imaging; the CAG showed there was stenosis greater than 90% in at least one major coronary artery.The CCCs were assessed in CAG by the Rentrop grading, and the CAG served as the gold standard to determine the accuracy of 64-MSCT angiography in detecting collateral circulations.All CCCs were grouped angiographieally into three groups of CC0, CC1 ,and CC2 by Werner collateral collection(CC) grading.In the 64-MSCT coronary angiography imaging, a new grading(MSCT-CC) was used to evaluate CCCs.The consistency between these two grading standards was analyzed by Kappa test.Resalts A total of 97 patients were entered into the study, among whom at least one CCC was found by CAG in 37 patients and at least one CCC was detected by 64-MSCT angiography.Taken the CAG results as the reference standard, the sensitivity and specificity of the 64-MSCT angiography in detecting patients with the CCCs were 89.2% (33/37) and 93.8% (60/64) respectively.The sensitivity of the 64-MSCT angiography detecting the CCCs was 75.8% (47/62). All the CCCs detected by CAG and 64-MSCT angiography were grouped into three groups according to Werner grading: 4 in CC0 group, 24 in CC1 group and 19 in CC2 group.The CCCs were grouped into three groups according to MSCT-CC: 7 in MSCT-CC0 group, 22 in MSCT-CC1 group and 18 in MSCT-CC3 group.The consistency of the two grading criteria was relatively high (Kappa = 0.857, P < 0.01).Conclusion 64-MSCT angiography can accurately evaluate the coronary collateral circulation.