Blood is a perishable product, and hence good management of inventories is crucial. Blood inventory management is a trade-off between shortage and wastage. The challenge is to keep enough stock to ensure a 100% supply of blood while keeping time expiry losses at a minimum. This article focuses on inventory management of red blood cells in hospital transfusion laboratories to derive principles of best practice and makes recommendations that will ensure losses due to time expiry are kept to a minimum. The literature was reviewed to identify available models for perishable inventory management. Historical data from the UK blood supply chain was analyzed to identify hospitals with good inventory management practice and low wastage levels. Transfusion laboratory managers in the selected hospitals were interviewed in 7 case studies with the aim of identifying drivers for low wastage and good inventory management practice. The findings from the case studies were compared with the literature. The extant literature asserts that the drivers for good inventory performance are the use of complex inventory models and algorithms. This study has found this not to be the case. Instead, good performance is driven by the quality of transfusion laboratory staff, who must be skilled, regularly trained, and experienced. Electronic crossmatching, transparency of the inventory, and simple management procedures also facilitate good performance.