To localize where urocortin is expressed in human tissue in an attempt to study its physiological functions. Methods: Expression of immunoreactive urocortin in different human tissue was examined using a specific urocortin antibody and the immunoperoxidase staining method. Results: Immunoreactive urocortin was observed in the anterior pituitary cells, decidual stromal cells, syncytiotrophoblasts, amnion epithelium, the vascular smooth muscles of myometrium, fallopian tube and small intestine. Conclusion: The study indicates that urocortin is expressed in some specific areas of human tissue. The data are consistent with the hypothesis that urocortin is produced locally as an endocrine factor, which may act as a neural regulator and a regulator of local blood flow.