Purpose: To evaluate the percentages of the left renal vein (LRV) variations and inferior vena cava (IVC) variations as well as the effect of gender on their frequencies. Materials and Methods: Contrast-enhanced abdominal helical computed tomography (CT) examinations of 1204 patients were retrospectively evaluated. Results: The correspondent percentages of the total LRV variations, retroaortic left renal vein (RLRV), and circumaortic LRV were 5.2%, 3.1%, and 2.1%, respectively. A statistically significant correlation was found between RLRV variation and gender (P=.036). Conclusions: Helical CT is an efficient, fast, easily applicable, and reliable imaging modality in demonstration of LRV variations and IVC variations. [ABSTRACT FROM AUTHOR]