The objective of the present study was to determine whether corticotropin-releasing hormone (CRH) influences porcine corpus luteum function. The gene expressions of CRH receptors (CRH-R) were determined in the CLs of Chinese Meishan pigs during the estrous cycle. The effects of CRH on progesterone (P), estradiol-17 beta (E) and prostaglandin (PG) F(2 alpha) secretion by cultured luteal cells were also investigated. Messenger RNAs of the CRH-R were clearly expressed in the CL throughout the estrous cycle, and the mRNA level was higher at the regressed stage than at the other stages (P<0.05). When the cultured luteal cells obtained from the mid-luteal stage CL (days 8-11) were exposed to CRH (50-5000 ng/ml), P secretion by the cells was significantly reduced at the highest dose.(P<0.05), whereas CRH had no effect on E and PGF(2 alpha) secretion by the cells. The overall results suggest that CRH inhibits local P production from luteal cells via its specific CRI-I-R, implying that CRH plays some roles in regulating porcine CL function during the estrous cycle, especially in the period of luteolysis.