© 2018 Elsevier Inc. All rights reserved. Testing of donor and recipient samples in the blood bank is a critical part of ensuring the safety of blood-product transfusion. Part of this chapter focuses on the regulatory aspects/safety measures that ensure blood samples used for testing are correctly identified. The remainder of the chapter focuses on testing that occurs in the blood bank including the following: proper identification of reagents; ABO typing and discrepancies; antibody screens and panels; and special techniques. Case scenarios are also included to reinforce knowledge and problem-solving skills for everyday clinical practice.