Purpose. Iatrogenic operative injury to the major veins is associated with significant morbidity and mortality. This study was conducted to review the pattern, management, and outcome of iatrogenic major venous injuries incurred during cancer surgery. Methods. We reviewed 24 patients with collective 30 venous injuries, evaluating clinical characteristics; operative and postoperative data, including location and type of venous injury, operative repair, blood loss, and transfusion requirements; and outcome. Results. Thirty venous and 12 associated arterial injuries were identified. The two most common sites of venous trauma were the iliac and femoral veins with 10 (33.3%) and 9 (30.0%) injuries, respectively. Twenty-three (76.7%) of the venous injuries were repaired primarily or with end-to-end anastomosis, while the remaining injuries required interposition grafts, patch venoplasty, or venous ligation. Postoperative revision procedures were performed in 3 (12.5%) patients. Perioperative mortality was 16.7% and major complications developed in 11 (45.8%) patients. Conclusions. Serious complications can be minimized by immediate recognition and prompt repair of iatrogenic vascular injuries. Close collaboration with a vascular surgeon during resection of tumors in proximity to the vascular structures may be helpful in preventing iatrogenic vascular injuries. In hospitals where tumor resection procedures are frequently performed, a vascular surgeon must be readily available.