Objective: To measure the e ects on mortality of the Modi ed Nutrition Risk in Critically Ill (mNUTRIC) and Nutritional Risk Screening 2002 (NRS-2002) scores in critical patients in the Intensive Care Unit (ICU) and to investigate the relationship between macronutrient de ciency and the mNUTRIC and NRS-2002 scores. Study Design: A descriptive study. Place and Duration of Study: The Department of Intensive Care, Burdur Public Hospital, Turkey, between 01st October 2019 and 01st November 2021. Methodology: The study included 311 patients aged >18 years, treated in the ICU for more than 7 days, and who received more than 48 hours of mechanical ventilation when required. The patients were divided into two groups according to calorie su ciency as those who received <70% or >70% of the energy calculated for the rst 5 days in ICU. Results: Of the 311 patients included in the study, the high nutritional risk was determined in 20.9% according to the NRS-2002, and 62.7% according to the mNUTRIC. In patients classi ed as having high nutritional risk in nNUTRIC (score e5), the in-hospital mortality risk was 3-fold higher (p<0.001), and in patients classi ed as having high nutritional risk in NRS-2002 (score e5), it was 2-fold higher (p=0.002). There was a strong relationship found between a high mNUTRIC score and insu cient calorie intake and there was no relationship between the mNUTRIC score and protein intake (p=0.058). Conclusion: While the mNUTRIC score was a signi cant scoring system to show 28-day in-hospital survival, the e cacy of NRS-2002 in showing mortality could not be demonstrated.