Objective: We evaluated the anatomy of the infrarenal portion of the human inferior vena cava and their ventral tributaries by video laparoscopy. Study Design: A total of 112 patients underwent laparoscopic para-aortic lymphadenectomy for gynecologic malignancies. All procedures were videotaped. The number and anatomic distribution of the infrarenal tributaries of the anterior part of the inferior vena cava was evaluated retrospectively from videotapes. The inferior vena cava was divided into 3 levels: the area of the bifurcation of the vena cava (level 1), the area between the bifurcation and the inferior mesenteric artery (level 2), and the area between the inferior mesenteric artery and the right ovarian vein (level 3). Results: Tributaries were found in level 1 in 65 (58%) patients, in level 2 in 22 (19.6%) patients, and in level 3 in 1 (0.9%) patient; in 24 (21.5%) patients no tributaries were found. A total of 237 tributaries was counted: 82.3% (195 of 237) were located at level 1, 17.3% (41 of 237) at level 2, and 0.4% (1 of 237) at level 3. Patients with tributaries had a mean of 3 tributaries in level 1, a mean of 1.7 tributaries in level 2, and 1 patient had 1 tributary in level 3. Conclusions: The ventral tributaries of the inferior vena cava show a specific distribution pattern. The knowledge of these anatomic landmarks can be important for laparoscopic surgeons to avoid accidental injury. (Am J Obstet Gynecol 1998;179:1295-7.)