Enzymes are molecules in most protein structures that catalyze important biochemical reactions in living organisms. But in the early 2000s, studies have shown that enzymes can also be used in drug synthesis. Chemical syntheses may damage the environment, require the use of chemicals that are expensive and potentially toxic to living organisms, often require additional steps for purification, and obtaining the desired enantiomers in these syntheses is difficult. For these reasons, researchers tended to use chemoenzymatic drug syntheses that are environmentally friendly, effective, efficient, and reusable. Enzymes are used in these syntheses. Hydrolase enzymes are one of the enzymes that are often used in drug synthesis. Hydrolases are enzymes that catalyze hydrolysis reactions. They are commonly used to obtain enantiomerically pure drug precursors in drug synthesis. Lipases were used in the synthesis of pregabalin which is an anticonvulsant drug, tryptase inhibitors, 15-deoxyspergualin which is an immunosuppressive agent, rasagiline used in the treatment of Parkinson disease, duloxetine which is an antidepressant drug, ibuprofen, ketoprofen, and naproxen which are nonsteroidal anti-inflammatory drugs and doxazosin which is an α1 – selective adrenergic antagonist. Esterases were used in the synthesis of doxazosin which is an α1 – selective adrenergic antagonist and glycosidases were used in the synthesis of rare ginsenosides. Epoxide hydrolases were used in the synthesis of propranolol which is a beta antagonist and linezolid which is an antibiotic. Peptidases were used in the synthesis of proteasome inhibitors, (+)-gamma-lactamases were used in the synthesis of abacavir which is an antiviral drug, and nitrilases were used in the synthesis of nicotinic acid. In addition, the importance and the advantages of chemoenzymatic syntheses, reactions catalyzed by these enzymes, results of synthesis, and the general information about used hydrolase enzymes were investigated in detail.