In enzymology, an agmatine deiminase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are agmatine and H<sub>2</sub>O, whereas its two products are N-carbamoylputrescine and NH<sub>3</sub>.
This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amidines. The systematic name of this enzyme class is agmatine iminohydrolase. This enzyme is also called agmatine amidinohydrolase. This enzyme participates in urea cycle and metabolism of amino groups.
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes , , , and .