In enzymology, a chitin synthase (EC 2.4.1.16) is an enzyme that catalyzes the chemical reaction

UDP-N-acetyl-D-glucosamine + [1,4-(N-acetyl-beta-D-glucosaminyl)]n ${\displaystyle \rightleftharpoons }$ UDP + [1,4-(N-acetyl-beta-D-glucosaminyl)]n⁺1

Thus, the two substrates of this enzyme are UDP-N-acetyl-D-glucosamine and [[[1,4-(N-acetyl-beta-D-glucosaminyl)]n]], whereas its two products are UDP and [[[1,4-(N-acetyl-beta-D-glucosaminyl)]n+1]].

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-N-acetyl-D-glucosamine:chitin 4-beta-N-acetylglucosaminyl-transferase. Other names in common use include chitin-UDP N-acetylglucosaminyltransferase, chitin-uridine diphosphate acetylglucosaminyltransferase, chitin synthetase, and trans-N-acetylglucosaminosylase. This enzyme participates in aminosugars metabolism.

Chitin Synthase is manufactured in the rough endoplasmic reticulum of fungi as the inactive form, zymogen. The zymogen is then packaged into chitosomes in the golgi apparatus. Chitosomes bring the zymogen to the hyphal tip of a mold or yeast cell membrane. Chitin synthase is placed into the interior side of the cell membrane and then activated.^{[citation needed]}

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• Sburlati A, Cabib E (1986). "Chitin synthetase 2, a presumptive participant in septum formation in Saccharomyces cerevisiae". J. Biol. Chem. 261 (32): 15147–52. PMID 2945823.