To (1) define the frequency of overall and postdischarge venous thromboembolism (VTE) after cancer surgery, (2) identify VTE risk for individual cancer operations, and (3) assess mortality rates in patients who experienced a VTE. Cancer is a known risk factor for VTE but less is known about VTE risk after specific cancer operations. Moreover, most cancer patients routinely receive VTE prophylaxis postoperatively while in the hospital, but few receive prolonged prophylaxis despite strong evidence it reduces postdischarge events. From 211 ACS NSQIP hospitals, 44,656 patients undergoing surgery for 9 cancers were identified (2006-2008). The frequency of VTE within 30-days of surgery was evaluated by cancer site and categorized as occurring before or after discharge. Multivariable logistic regression models were constructed to assess risk factors associated with VTE. VTE occurred in 1.6% of all patients, most frequently after esophagogastric (4.2%) and hepatopancreaticobiliary (3.6%) surgery. Overall, 33.4% of VTEs occurred postdischarge (from 17.9% for esophagogastric to 100% for endocrine operations). Factors associated with VTE were age (≥65 years), cancer/procedure type, metastatic disease, congestive heart failure, body mass index (BMI; ≥25 kg/m(2)), ascites, thrombocytosis (>400,000 cells/mm(3)), albumin (<3.0 g/dL), and operation duration (>2 hours; all P < 0.001). Overall VTE was significantly more likely after gastrointestinal, lung, prostate, and ovarian/uterine operations (all P < 0.001). In those experiencing a VTE, mortality increased over 6-fold (8.0% vs. 1.3%; P < 0.001). One-third of VTE events in cancer surgery patients occurred postdischarge. Postoperative VTE was associated with operation type. Routine postdischarge VTE prophylaxis should be considered for high-risk patients.