We present a rare case associating inferior vena cava's (IVC) complex variations. Anatomical, embryological and clinical aspects are discussed. Duplication's discovery was fortuitous during an abdominal ultrasound and was confirmed by the CT scan. The latter also highlighted azygos continuation, retro aortic renal vein and an iliac venous anomaly. These variants are important to know in order to be able to differentiate them from lymphadenopathy, para-vertebral masses, and aortic pathologies. It is necessary to report them before any retroperitoneal surgery or interventional vascular procedure.