胰蛋白酶（英语：trypsin）是一种酶。

胰蛋白酶在小肠工作，它会将蛋白质水解为肽，进而分解为氨基酸。这是蛋白质能被人体吸收的必要过程。这种酶的作用原理和其他丝氨酸蛋白酶差不多。

胰蛋白酶的最佳pH值约为8，温度约为37℃。

胰脏制造的是没有活性的胰蛋白酶原。它分泌到小肠后，小肠内的肠肽酶会活化它，令它成为胰蛋白酶。已经变成胰蛋白酶的，能活化更多胰蛋白酶原，这种过程即自动催化，所以只需少量肠肽酶便能开始消化反应。这种过程能避免胰脏被活化的酶消化。

Trypsin (EC3.4.21.4) is a serine protease from the PA clan superfamily, found in the digestive system of many vertebrates, where it hydrolyses proteins. Trypsin is formed in the small intestine when its proenzyme form, the trypsinogen produced by the pancreas, is activated. Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine, except when either is followed by proline. It is used for numerous biotechnological processes. The process is commonly referred to as trypsin proteolysis or trypsinisation, and proteins that have been digested/treated with trypsin are said to have been trypsinized.