We are reporting a series of four cases of acute liver failure (ALF) requiring liver transplantation (LT) due to acute HAV.<h4>Methods</h4>Chart review and case descriptions of four patients with acute HAV-related ALF who were expeditiously evaluated, listed as Status 1A, and who underwent LT between August 2019 and October 2019 at Thomas Jefferson University Hospital.<h4>Results</h4>All four patients presented with acute hepatocellular jaundice and had a positive HAV IgM, and all other causes of ALF were excluded. The gene discussed is CD40LG; the disease is acute liver failure.