Pyruvate kinase (PK) deficiency is an inherited disease that affects red blood cells and manifests as hemolytic anemia. It is a lifelong condition, with symptoms that range from mild to severe. Despite an ever-growing understanding of its pathophysiology, etiology, and epidemiology, and an active research program, PK deficiency remains unfamiliar to many medical practitioners. PK deficiency is clinically heterogeneous, so healthcare professionals need to consider the possibility of this disorder in all patients with a congenital hemolytic anemia.