Abstract: Prostaglandins is a family of eicosanoids, which have many biological functions. Cyclooxygenase is the key enzyme of the prostaglandins' biosynthesis and it has two isoforms:COX-1 and COX-2. Many researchs indicate that prostaglandins and cyclooxygenase play positive protective role in gastrointestinal tract. In this review, the role of prostaglandins and cyclooxygenase in radiation-induced gastrointestinal injury, as well as their biochemistry and physiology is summarized.