During the last ten years, research has been flourishing on what was the first peptide hormone to have its structure completely elucidated and the first to be chemically synthesized. Oxytocin is involved in virtually all activities related to reproduction, as well as in some that have less apparent connection with reproduction. Representing the current state of knowledge, contributions from the April-May 1995 conference discuss synthesis and regulation; central control of oxytocin neurones; oxytocin and behavior (including a paper on the molecular basis of monogamy and another on reduction of plasma oxytocin levels in patients with major depression); the oxytocin receptor; agonists, antagonists, and clinical application; and comparative endocrinology of oxytocin-like peptides.