Substance P belongs to a group Neurikinins (NKs), small peptides that are broadly distributed in the central nervous system and peripheral nervous system. It is a small peptide that transmits pain signals from sensory nerves to the central nervous system. it is found in the spinal cord and brain. For substance P to transmit its signal, it must bind to a molecule that will relay the signal to the CNS, that molecule called as neurokinin 1 receptor. The roles of substance P is pain induction, vasodilation effect, Inflammation, Induction of emesis, Role in Cell growth and Proliferation, Role in the regulation of emotions and stress. Still research of SP is going on Arthritis and Alzheimer’s disease. So SP is having greater importance in nearby future in the medical research.