Corticotropin-releasing hormone (CRH) is a hypothalamic neuropeptide that has been identified also in several peripheral tissues, including organs of the reproductive system. In man, CRH is synthesized and released by the gonads, the placenta, maternal decidua, and the epithelial endometrium. So far, CRH has been demonstrated in endometrial stromal cells only after decidualization. The aim of this study was to seek evidence of the production and secretion of CRH by endometrial stromal cells in different phases of the menstrual cycle and to look for gene expression of the recently identified CRH receptor R1. Total RNA was extracted from stromal cells monolayers established from endometrial samples collected during both proliferative and secretive phases. After reverse transcription, polymerase chain reaction (PCR) amplification was carried out using primers specific to CRH and to CRH receptor R1, resulting in the expected bands, respectively 233 bp for CRH and 274 bp for CRH-R1. The identity of the obtained CRH PCR product was confirmed by restriction enzyme analysis and by Southern blotting. Purification by high performance liquid chromatography (HPLC) of stromal cell culture medium revealed a major peak of CRH immunoreactivity coeluting with the standard CRH(1-41), thus indicating the secretion of the mature peptide. Our study demonstrates the synthesis and secretion of CRH by endometrial stromal cells at all phases of the menstrual cycle. We also demonstrate the expression of the CRH receptor R1 gene. It can be hypothesized that CRH contributes via autocrine/paracrine mechanisms to endometrial physiology.