Thymosin Alpha-1 (Tα1) also called Zadaxin, is a peptide that occurs naturally in thymus gland, which represents a crucial organ for body immune system. Thymosin-Alpha-1 also plays important role in the regulation of immune responses and functions. It was isolated from tissue of the thymus gland for the first time in 1972 and has been used in treating immunocompromised states, malignancies, and enhancing vaccine response. It has been studied for cystic fibrosis, sepsis, various infections, chronic hepatitis or cancer. Thymosin Alpha-1 is approved in 35 developing countries for the treatment of hepatitis B and C.