Northfield Laboratories, Inc., a development stage company, engages in the research, development, testing, manufacture, marketing, and distribution of hemoglobin-based blood substitute products. It primarily develops PolyHeme, a human hemoglobin-based oxygen-carrying red blood cell substitute for the treatment of life-threatening blood loss when an oxygen-carrying fluid is required and red blood cells are not available. The company was founded in 1985 and is headquartered in Evanston, Illinois.