Background: There is an international consensus that nutrition screening be performed at the hospital; however, there is no “best tool” for screening of malnutrition risk in hospitalized patients. Objective: To evaluate (1) the accuracy of the MUST (Malnutrition Universal Screening Tool), MST (Malnutrition Screening Tool), and SNAQ (Short Nutritional Assessment Questionnaire) in comparison with the NRS-2002 (Nutritional Risk Screening 2002) to identify patients at risk of malnutrition and (2) the ability of these nutrition screening tools to predict morbidity and mortality. Methods: A specific questionnaire was administered to complete the 4 screening tools. Outcomes measures included length of hospital stay, transfer to the intensive care unit, presence of infection, and incidence of death. Results: A total of 752 patients were included. The nutrition risk was 29.3%, 37.1%, 33.6%, and 31.3% according to the NRS-2002, MUST, MST, and SNAQ, respectively. All screening tools showed satisfactory performance to identify patients at nutrition risk (area under the receiver operating characteristic curve between 0.765–0.808). Patients at nutrition risk showed higher risk of very long length of hospital stay as compared with those not at nutrition risk, independent of the tool applied (relative risk, 1.35–1.78). Increased risk of mortality (2.34 times) was detected by the MUST. Conclusion: The MUST, MST, and SNAQ share similar accuracy to the NRS-2002 in identifying risk of malnutrition, and all instruments were positively associated with very long hospital stay. In clinical practice, the 4 tools could be applied, and the choice for one of them should be made per the particularities of the service.