A significant association between elevated white blood cell (WBC) count and mortality in patients with cancer has been reported,but the predictive value of elevatedWBC on mortality in cancer patients with acute venous thromboembolism (VTE) has not been explored. RIETE is an ongoing registry of consecutive patients with acute VTE. We compared the three-month outcome of cancer patients with acuteVTE according to theirWBC count at baseline. As of May 2007, 3805 patients with active cancer and acuteVTE had been enrolled in RIETE. Of them, 215 (5.7%) had low- (<4,000 cells/µl), 2,403 (63%) normal- (4,000–11,000 cells/µl), 1,187 (31%) elevated (>11,000 cells/µl) WBC count. During the study period 190 patients (5.0%) had recurrent VTE, 156 (4.1%) major bleeding, 889 (23%) died (399 of disseminated cancer, 113 of PE, 46 of bleeding. Patients with elevated WBC count at baseline had an increased incidence of recurrent VTE (odds ratio [OR]: 1.6; 95% confidence interval [CI]:1.2–2.2),major bleeding (OR:1.5;95% CI:1.1–2.1) or death (OR:2.7;95% CI:2.3–3.2).Most of the reported causes of death were significantly more frequent in patients with elevated BC count.Multivariate analysis confirmed that elevated WBC count was independently associated with an increased incidence of all three complications. In conclusion, cancer patients with acute VTE and elevated WBC count had an increased incidence of VTE recurrences,major bleeding or death. This worse outcome was consistent among all subgroups and persisted after multivariate adjustment.