The RIETE-VTE score was derived to risk-stratify patients with cancer-associated venous thromboembolism (CAT).To externally validate the RIETE-VTE score and to compare its prognostic performance with the modified Ottawa score.We studied 178 elderly patients with CAT in a prospective multicenter cohort and assessed 30-day all-cause mortality, 90-day overall complications (mortality, major bleeding, or venous thromboembolism [VTE] recurrence), and 6-month VTE recurrence. Patients were stratified into RIETE-VTE and modified Ottawa score risk classes (low, intermediate, high). We compared the discriminative power (area under the receiver operating characteristic [ROC] curve) to predict mortality, overall complications, and VTE recurrence.Fifteen patients (8.4%) died within 30 days, 42 (23.6%) experienced an overall complication by day 90, and 6 (3.4%) had recurrent VTE within 6 months. The RIETE-VTE and the modified Ottawa score classified similar proportions of patients as low risk (35.4% versus 31.5%; P = .37). No low-risk patient died within 30 days. Low-risk patients identified by the RIETE-VTE and modified Ottawa score had similar rates of overall complications (7.9% versus 8.9%) and VTE recurrence (1.6% versus 1.8%). The modified Ottawa score and the RIETE-VTE score had similar areas under the ROC curve for predicting all-cause mortality (0.84 versus 0.75; P = .21), overall complications (0.74 versus 0.68; P = .26), and VTE recurrence (0.67 versus 0.64; P = .78).Both the RIETE-VTE and modified Ottawa score accurately identified elderly patients with CAT who are at low risk for short-term mortality and who are potential candidates for outpatient care.