Although patients with hematological malignancies carry a non-negligible risk of venous thromboembolic events (VTE), no risk assessment models (RAMs) have been developed and validated to predict this risk during their hospital stay. Moreover, the performance of RAMs developed to predict the thromboembolic and hemorrhagic risk in hospitalized medical patients has never been assessed in this specific population. In this observational study we sought to assess the incidence of VTE and hemorrhagic events (HE), to evaluate pharmacological prophylaxis use, and to test existing RAMs for TE and HE (Padua Predictions Score, PPS, and Improve Bleeding Score, IBS, respectively) in a population of 514 hematological patients at their first hospital admission. 165 patients were found to be at high thromboembolic and 114 at high hemorrhagic risk according to PPS and IBS; a total of 148 patients received pharmacological prophylaxis with low-molecular weight heparin (LMWH). An incidence of VTE (3.11%) and HE (1.75%) was found, with most thrombotic (15/16) and hemorrhagic (8/9) events occurring in patients not receiving prophylaxis. At the univariate analysis, the diagnosis of acute leukemia was significantly associated with an increased risk of VTE, whereas prophylaxis was found to be protective. However, at the multivariate analysis the statistical significance was lost for both of these variables (HR = 2.76, p = 0.218 and HR = 0.22, p = 0.170, respectively). PPS poorly performed in this population, but no other factors associated with VTE were found. Larger, multicenter studies to develop better RAMs tailored to HM patients are needed to improve VTE management in this population.