Prekallikrein deficiency is a disorder that often remains undiagnosed. Prekallikrein activates factor XII, which initiates the intrinsic coagulation pathway. Prekallikrein deficiency results in prolonged Partial Thromboplastin Time and Activated Clotting Time in absence of anticoagulants or active bleeding. This case report describes the anesthesia management of a patient with Prekallikrein deficiency who underwent cardiac surgery with Cardiopulmonary Bypass for correction of a congenital cardiac malformation. We highlight the importance of understanding the different tests available for the diagnosis of coagulation factors deficiency during administration of heparin in the setting of cardiovascular procedures under general anesthesia.