Cancer patients with acute venous thromboembolism (VTE) have an increased incidence of recurrences and bleeding complications while on anticoagulant therapy. Methods RIETE is an ongoing registry of consecutive patients with acute VTE. We tried to identify which cancer patients are at a higher risk for recurrent pulmonary embolism (PE), deep vein thrombosis (DVT) or major bleeding. Up to May 2007, 3,805 cancer patients had been enrolled in RIETE. During the first three months of follow-up after the acute, index VTE event, 90 (2.4%) patients developed recurrent PE, 100 (2.6%) recurrent DVT, 156 (4.1%) had major bleeding. Forty patients (44%) died of the recurrent PE,46 (29%) of bleeding. On multivariate analysis, patients aged <65 years (odds ratio [OR]: 3.0; 95% confidence interval [CI]: 1.9-4.9), with PE at entry (OR: 1.9; 95% CI: 1.2-3.1), or with <3 months from cancer diagnosis to VTE (OR: 2.0; 95% CI: 1.2-3.2) had an increased incidence of recurrent PE. Those aged <65 years (OR: 1.6; 95% CI: 1.0-2.4) or with <3 months from cancer diagnosis (OR: 2.4; 95% CI: 1.5-3.6) had an increased incidence of recurrent DVT. Finally, patients with immobility (OR: 1.8; 95% CI: 1.2-2.7), metastases (OR: 1.6; 95% CI: 1.1-2.3), recent bleeding (OR: 2.4; 95% CI: 1.1-5.1), or with creatinine clearance <30 ml/min (OR: 2.2; 95% CI: 1.5-3.4), had an increased incidence of major bleeding. With some variables available at entry we may identify those cancer patients with VTE at a higher risk for recurrences or major bleeding.