Blood transfusion is a critical component of patient management in intensive care units (ICUs), significantly impacting outcomes for critically ill patients. This chapter explores the comprehensive role of pharmacists in ensuring the rational use of blood products in the ICU, emphasizing their contributions to medication management, protocol development, patient consultation, reaction management, education, and quality improvement. By detailing the types of blood components, compatibility testing, and evidence-based transfusion thresholds, the chapter underscores the importance of interdisciplinary collaboration in optimizing transfusion practices. It also addresses the pharmacologic measures and best practices for minimizing transfusion-related complications, highlighting the pharmacist’s role in promoting patient safety and enhancing clinical outcomes.