Objective : To determine whether cyclooxygenase (COX)-1 and COX-2 are expressed differentially during the whole gestational period in the pregnant human uterine cervix and if they are involved in the process of labor. Methods : Nine patients were matched for obstetrical history and maternal age were divided into an abortion group who aborted between 13 and 16 weeks(n=3), a preterm group who delivered between 20 and 37 weeks(n=3), and a term group who delivered between 37 and 42 weeks of gestation(n=3). Immediately after vaginal delivery cervical biopsy samples were obtained and immunohistochemically stained for COX-1 and COX-2 and the degree of staining was evaluated by H-scoring system. Results : Expression of COX-1 and COX-2 was found in epithelial and stromal cells of uterine cervical tissues of preterm and term group. The immunohistochemical expression of COX-1 and COX-2 was strongest in the term group compared to the preterm group in stromal cells(HSCORE : 2.0 vs. 4.0 ; 2.0 vs. 3.0), and in epithelial cells(HSCORE : 1.0 vs. 3.0 ; 1.0 vs. 3.0). Conclusion : Although small amount of the groups were investigated, in the pregnant human uterine cervix, COX-1 and COX-2 are found to be expressed, and both shows the strongest expression in term cervical tissue. It is suggested that the uterine cervix, under the control of prostaglandins, is actively involved in the process of labor, and it is thought that the role of COX-1 and COX-2 is more important in parturition process with advancing gestational age.