Anemia of multifactorial etiology is common among critically ill patients and several arbitrary transfusion thresholds have been proposed. Transfusion of red blood cells has been well established to increase morbidity and even mortality among critically ill patients. Several randomized controlled studies have evaluated the use of a restrictive compared to a more liberal transfusion strategy in the critically ill. A transfusion threshold of 7 g/dL appears to be generally safe, especially in the younger age group without significant comorbidities. Besides, a restrictive transfusion strategy reduces the incidence of transfusion-related complications. However, the decision to transfuse needs to be individualized depending on the clinical situation, balancing putative benefits against possible complications.