Sermorelin, sometimes called GRF 1-29, is a growth hormone

Growth hormone

Growth hormone is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans and other animals. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior...

 releasing hormone analogue. It is a 29-amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 polypeptide representing the 1-29 fragment from endogenous human growth hormone releasing hormone

Growth hormone releasing hormone

Growth-hormone-releasing hormone , also known as growth-hormone-releasing factor , somatoliberin or somatocrinin, is a releasing hormone for growth hormone...

, and is thought to be the shortest fully functional fragment of GHRH. It is used as a test for growth hormone secretion. It is also used as doping substance in sports.
Used extensively in Anti-aging Therapy often in conjunction with Testosterone in men. Safer alternative to Human Growth Hormone.