Zymase is an enzyme complex that catalyze glycolysis, the fermentation of sugar into ethanol and carbon dioxide. As the conversion takes place, the reaction will gradually slow down. They occur naturally in yeasts. See alcohol dehydrogenase.

Zymase was first isolated from the yeast cell in 1897 by a German chemist named Eduard Buchner who fermented sugar in the laboratory. A British chemist by the name of Sir Arthur Harden divided zymase into two varieties dialyzable and nondialyzable in 1905.

Zymase is also the brand name of the generic enzyme mixture pancrelipase, a dietary supplement containing the enzymes amylase, peptidase, and lipase. It is sold to help digestion in people who do not produce enough of their own digestive enzymes.