In enzymology, a tryptophan dimethylallyltransferase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are dimethylallyl diphosphate and L-tryptophan, whereas its two products are diphosphate and 4-(3-methylbut-2-enyl)-L-tryptophan.
This enzyme belongs to the family of transferases, specifically those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is . Other names in common use include , , , DMAT synthetase, and .