Recently a new member of the corticotropin-releasing factor (CRF) family has been cloned and named urocortin. It has been localized in rat brain and to human chromosome 2. The present study investigated whether human placenta and related tissues express mRNA and immunoreactive urocortin. Using specific oligonucleotide primers, reverse transcriptase-polymerase chain reaction experiments were performed on total RNA isolated from human placenta and decidua collected both at early stage of gestation (8-11 weeks) and at term (39-40 weeks). In addition, experiments were also done on specimens of amnion and chorion collected at term. Independently from the gestational age, placental and decidual cells expressed urocortin mRNA, with a 145 bp DNA band corresponding to the expected length. The expression of urocortin mRNA was also found in amnion and chorion. Using specific antiserum and an immunoperoxidase technique, immunoreactive urocortin was then localized in syncytiotrophoblast cells and in some extent in cytotrophoblast cells of placental villi at term, as well as in fetal membranes and maternal decidua. The present findings revealed that human placenta and gestational related tissues express human urocortin gene and localize immunoreactive urocortin, supporting the concept that these tissues are capable of expressing a large number of neuroendocrine peptides.