AIMS: Anemia is common in the old and often observed in critically ill patients. Increased age is associated with higher mortality following a COVID-19 infection, making old patients prone to poor outcomes. We investigated whether anemia at admission to the ICU or the need for blood transfusion was associated with 90-day mortality in older, critically ill COVID-19 patients. METHODS: In this prospective multicenter study, the 90-day mortality of COVID-19 patients≥70 years treated in 138 intensive care units (ICU) was analyzed. Associations between anemia (WHO definition) at admission and discharge from ICU and the use of red blood cell (RBC) transfusions with mortality were assessed. Hemoglobin thresholds of RBC transfusions in old, critically ill COVID-19 patients were recorded. RESULTS: In 493 patients (350 anemic, 143 non-anemic), anemia (WHO definition) at the time of ICU admission was not associated with impaired overall survival. Transfusion and severe anemia (hemoglobin≤10 g/dL) at ICU discharge were independently associated with a higher risk of 90-day mortality. CONCLUSION: The need for red blood cell transfusions and severe anemia at ICU discharge, but not at the timepoint of admission, were independently associated with 90-day mortality in critically-ill old COVID-19 patients.