Prostaglandin E2 (PGE2) may regulate uterine activation and cervical ripening for labor through specific contractile and relaxatory receptors (EP1-4). The aim of this study was to determine the expression of PGE2 receptor isoforms in pregnant rat cervix during RU486-induced labor and progesterone supplementation to delay labor. Localization and expression of cervical PGE2 receptors were evaluated, and quantitative real-time polymerase chain reaction (PCR) for EP1-4 was performed. EP1-4 were found in both cervical epithelium and smooth muscle. RU486 treatment increased EP2 and EP4 messenger RNA (mRNA) and protein expression. Progesterone treatment had no effect on EP2 and EP4 mRNA expression but decreased EP4 protein. Hormonal manipulation resulted in differences in cellular localization of EP1 and EP3 in cervical epithelial cells, suggesting a specific role in that cell. Progesterone differentially regulates the expression of PGE2 receptor isoforms in the cervix. Elucidating the regulation of PGE2 receptors may facilitate improved approaches to the prevention and treatment of preterm labor.