Objective：To investigate the value of computed tomography venography/angiography（CTV/A） via both great saphenous veins in the imaging diagnosis of iliac vein compression syndrome（IVCS）. Methods：A retrospective analysis was performed on 109 cases（49 males and 60 females） diagnosed as IVCS by digital subtraction angiography. They were randomly divided into group A（57 cas－es；25 males and 32 females） and group B（52 cases；24 males and 28 females）. Group A and group B were injected with a contrast agent through both great saphenous veins（below the knee joint） and both dorsalis pedis veins，respectively. A bolus tracking scan was performed in both groups；we monitored the abdominal aorta and the inferior vena cava in group A and group B，respectively. Arteri－ovenous nicking and distorted open collateral vessels were displayed by postprocessing methods such as three-dimensional volume rendering，maximum intensity projection，multiplanar reformation，and curved planar reconstruction. Three experienced diagnosticians evaluated the image quality，abdominal aorta-inferior vena cava contrast ratio（direct sign），and collateral display rate（indirect sign）. Results：①The display rate of the distorted pelvic vein，caudal venous plexus，abdominal wall branches was significantly higher in group A than in group B（58.14% vs. 13.95%，P<0.001）；the display rate of varicose veins in both lower limbs was not significantly different between group A and group B（98.83% vs. 96.51%，P=0.312）. ②There was no significant difference in the vascular density of the inferior vena cava trunk between group A and group B（354.07±26.49 HU vs. 303.59±30.57 HU，t=11.57，P<0.001）；group A had a significantly higher vascular density of the iliac artery trunk than group B（177.28±14.95 HU vs. 74.24±13.49 HU，t=47.45，P>0.001）. ③The incidence of contrast agent eddy current was significantly lower in group A than in group B（23.26% vs. 62.79%，P<0.001）. ④Group A had a significantly higher diagnostic accuracy rate of IVCS than group B（93.6% vs. 10.22%，P<0.001）. Conclusion：Lower limb CTV/A via both great saphe－nous veins can clearly demonstrate iliac arteriovenous anatomy and the direct and indirect signs of IVCS，thus improving image quality and the diagnostic accuracy rate of IVCS.