Malnutrition rates for critically ill patients being admitted to the intensive care unit (ICU) are reported to range from 38% to 78%. Malnutrition in the ICU is associated with increased mortality, morbidity, length of hospital admission, and ICU readmission rates. The high volume of ICU admissions means that efficient screening processes to identify patients at nutritional or malnutrition risk are imperative to appropriately prioritise nutrition intervention. As the proportion of noninvasively mechanically ventilated patients in the ICU increases, the feasibility of using nutrition risk screening tools in this population needs to be established. The aim of this study was to compare the feasibility of using the Malnutrition Universal Screening Tool (MUST) with the modified NUtriTion Risk In the Critically ill (mNUTRIC) score for identifying patients at nutritional or malnutrition risk in this population. A single-centre, prospective, descriptive, feasibility study was conducted. The MUST and mNUTRIC tool were completed within 24 h of ICU admission in a convenience sample of noninvasively mechanically ventilated adult patients (≥18 years) by a trained allied health assistant. The number (n) of eligible patients screened, time to complete screening (minutes), and barriers to completion were documented. Data are presented as mean (standard deviation), and the independent samples t-test was used for comparisons between tools. Twenty patients were included (60% men; aged 65.3 13.9 years). Screening using the MUST took a significantly shorter time to complete than screening using the mNUTRIC tool (8.1 2.8 vs 22.1 5.6 minutes; p = 0.001). Barriers to completion included obtaining accurate weight history for the MUST and time taken for collection of information and overall training requirements to perform mNUTRIC. The MUST took less time and had fewer barriers to completion than mNUTRIC. The MUST may be the more feasible nutrition risk screening tool for use in noninvasively mechanically ventilated critically ill adults.