OBJECTIVE: The increasing use of computed tomography (CT) angiography has led to more frequent diagnoses of celiac artery compression (CAC) by the median arcuate ligament (MAL). The signs of CAC by the MAL have been described as stenosis and a hook or J appearance on sagittal views. The importance of the "hook signal," however, has not been documented by studies of the normal anatomy of the celiac axis. METHODS: CT angiography images of 344 completely asymptomatic, live kidney donors (without history of chronic abdominal pain or weight loss) were reviewed. The angle of emergence (AE) of the celiac axis from the aorta and the angle of upward or downward shifting of the celiac axis before its first branch (fold angle [FA]) were measured. Weight, height, and body mass index were obtained from our electronic database, and correlations with the angles measured were tested. The occurrence of stenosis >50% at the origins of the celiac axis was also determined in the sample. RESULTS: Measurements were possible in 321 cases. The celiac axis was found to leave the aorta at an angle of <90 degrees in all patients (AE range, 7-83 degrees) and <45 degrees in 292 (90%) patients. The FA ranged from 66 to 208 degrees. Before the first branch, the celiac trunk shifted upward in 306 (95%) patients, remained straight in just one of them, and shifted downward in 14 (4%). The AE was positively correlated with weight in women. The FA was negatively correlated with weight in men and women. Body mass index was positively correlated with AE and negatively correlated with FA in both men and women. In 11 cases (3.4%), stenosis >50% was found at the origin of the celiac axis. In only two patients, the celiac axis had an upward slope after the stenosis, which could be interpreted as a hook shape. CONCLUSIONS: The normal anatomy of the celiac axis, when seen on CT angiography images, demonstrates that it exits the aorta downward and then shifts upward. This hook or J shape should not be interpreted as resulting from external compression. CAC by the MAL occurs in 3.42% of the normal asymptomatic population; a hook or J shape is not visible in most cases in that subgroup.