ABSTRACTThe natural extracellular hemoglobin of the lugworm Arenicola marina (AmHb) has many interesting characteristics: It carries 40 times more oxygen than human hemoglobin; has anti‐inflammatory, antibacterial, and antioxidant properties; and is 250 times smaller than a red blood cell. It is nontoxic and nonimmunogenic. It is thus a very promising hemoglobin‐based oxygen carrier. AmHb is extracted and purified in GMP conditions to produce a therapeutic molecule, called M101. It is used in various forms (liquid, hydrogel, and lyophilized) to respond to different situations of hypoxia in the healthcare field, such as organ preservation prior to transplantation, wound and burn healing, periodontitis, sickle cell disease, and red blood cell transfusions, particularly in emergency situations. Given these remarkable oxygen transport capacities, M101 could be misused for doping purposes. This article presents current and future developments in this molecule.