Malic acid is an organic compound with the molecular formula C₄H₆O₅. It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms (L- and D-enantiomers), though only the L-isomer exists naturally.

Malic acid is a chemical found in certain fruits and wines. It is used to make medicine. People take malic acid by mouth for tiredness and fibromyalgia. In foods, malic acid is used as a flavoring agent to give food a tart taste

Malic acid is found naturally in fruits including apricots, blackberries, blueberries, cherries, grapes, peaches, pears, and plums. Malic acid is also found in some citrus fruits.