PURPOSE: To compare the usefulness of test bolus examination in three-dimensional contrast enhanced MR angiography of the carotid artery with that of the fixed delay time method. MATERIALS AND METHODS: Sixty consecutive patients (mean age, 60.1 years) in whom carotid arterial disease was suspected and who were examined during a 17-month period were divided into two equal groups. For group A, a fixed delay time of 5 secs was used, while for group B, the delay time of the test bolus examination was calculated from the signal intensity versus time curve of the carotid artery, obtained after the test injection of 1 ml contrast material into the right brachal vein. Overall image quality, discrimination between the arterial and the venous phase, and the contrast-to-noise ratio(CNR) of the carotid artery were compared between the two groups. Overall image quality was classified as excellent, good, moderate or poor, and discrimination between the two phases was graded IV-I according to the degree of jugular venous enhancement. RESULTS: In group A, overall image quality of the carotid artery was classified as excellent or good in 13 (43.3%)and 9 (30.0%) cases, respectively, while in group B the corresponding figures were 23 (76.7%) and 5 (16.7%). The differences between the two groups were statistically significant (p<0.05). In terms of discrimination between the arterial and venous phase, 20 (66.7%) of the 30 cases in group A were assigned grade IV or III, while 28 (93.3%) of the 30 in group B were assigned these same grades (p<0.05). The CNR of the carotid artery was higher in group B(67.1 +/-16.1) than in group A(27.3 +/-17.8), with statistical significance(p<0.05). CONCLUSION: For examination of the carotid artery, contrast enhanced MR angiography using a test bolus is su-perior to the fixed delay time method.