Agmatine, also known as (4-aminobutyl)guanidine, is an aminoguanidine that was discovered in 1910 by Albrecht Kossel.

Agmatine is a chemical substance which is naturally created from the chemical arginine. Agmatine has been shown to exert modulatory action at multiple molecular targets, notably: neurotransmitter systems, ion channels, nitric oxide (NO) synthesis and polyamine metabolism and this provides bases for further research into potential applications.