This gene encodes a member of the serpin family of serine protease inhibitors. The protein is a major inhibitor of plasmin, which degrades fibrin and various other proteins. Consequently, the proper function of this gene has a major role in regulating the blood clotting pathway. Mutations in this gene result in alpha-2-plasmin inhibitor deficiency, which is characterized by severe hemorrhagic diathesis. Multiple transcript variants encoding different isoforms have been found for this gene.