BACKGROUND: Malnutrition status, body composition indicators and bioimpedance (BIA) parameters have been associated with increased risk of death in several pathologies. The aim of this study was to describe the associations between phase angle (PhA) indicators obtained by BIA with length of hospital stay, days on mechanical ventilation and 60-day mortality in critically ill patients infected with SARS-COV-2. METHODS: This is a prospective cohort of mechanically ventilated patients with COVID-19. We assessed nutritional risk and body composition with BIA within 48 hours from ICU admission. Logistic and linear regression models were used to analyze the association between variables and clinical outcomes. Survival analysis by PhA value was performed using Kaplan-Meier curves. RESULTS: Sixty-seven patients were included. PhA (OR 0.36, p = 0.002), SPA (OR 0.45, p = 0.001) and extracellular water/total body water ratio (OR 3.25, p = 0.002) were significant predictors of 60-day mortality. PhA <3.85 degrees in females and <5.25 degrees in males showed good (AUC 0.83, p = 0.03) and fair (AUC 0.74, p = 0.003) discrimination, respectively, for mortality prediction. Using cut-off values, low PhA was associated with a significantly increased risk of 60-day mortality (HR 3.08, 95%CI 1.12-8.41, p = 0.02). No association was detected for SPA. CONCLUSION: Low PhA values could be a predictor of 60-day mortality in COVID-19 critically ill patients. This biological marker could be incorporated as a part of nutritional and mortality risk assessment in this population. This article is protected by copyright. All rights reserved.