Inpatient venous thromboembolism (VTE) is a priority preventable illness; risk in cancer varies and prophylaxis is inconsistently used. A previously validated tool (Khorana Score, [KS]) identifies VTE risk in cancer outpatients with 5 easily available variables but has not been studied in the inpatient setting. We evaluated the validity of KS in predicting VTE risk in hospitalized cancer patients. We conducted a retrospective cohort study of consecutive oncology inpatients at the Cleveland Clinic from 11/2012 to 12/2014 (n = 3531). Patients were excluded for VTE on admission (n = 304), incomplete KS data (n = 439) or other reasons (n = 8). Data collected included demographics, cancer type, length of stay (LOS), anticoagulant use, and laboratory values. Multivariate risk factors were identified with stepwise logistic regression, confirmed with bootstrap analysis. Of 2780 patients included, 106 (3.8%) developed VTE during hospitalization. Median age was 62 (range, 19-98) years and 56% were male. Median LOS was 5 (range, 0-152) days. High risk KS (≥ 3) was significantly associated with VTE in uni- and multivariate analyses (OR 2.5, 95% [confidence interval] CI 1.3-4.9). Other significant variables included male gender (OR 1.67, 1.1-2.53), older age (OR 0.86, 0.75-0.99) and use of anticoagulants (OR 0.57, 0.39-0.85). Recursive partitioning analysis suggested optimal cut point for KS is 2 (OR 1.82, 1.23-2.69). This is the first report validating KS as a risk tool to predict VTE in hospitalized cancer patients. Using this tool could lead to more consistent and successful application of inpatient thromboprophylaxis.