Vasopressin expression in the brain is under the control of different molecular mechanisms. For example, vasopressin (VP) expression in the bed nucleus of the stria terminalis (BNST) and medial amygdaloid nucleus (MeA) critically depends on estrogen stimulation, but VP expression in the suprachiasmatic nucleus (SCN) and paraventricular and supraoptic nucleus (PVN and SON) proceeds in the absence of gonadal hormones. Possibly related to this, virtually all VP-expressing neurons in the BNST and MeA express estrogen receptor alpha (ERα) whereas VP-expressing neurons in other areas express little or no ERα. Thus, ERα may mediate estrogen effects on VP transcription in the BNST and MeA perhaps by acting directly on the VP gene. Previous work using artificial reporter assays had indeed indicated that there is a putative estrogen response element (ERE) in the control region of the VP gene. Here, we use chromatin immunoprecipitation (ChIP) to compare ERα binding to the VP gene in brain tissue that includes the BNST or SCN. We also included cortex tissue, in which no VP expression has been demonstrated. We observed ERα binding specifically to the VP gene in tissue that included the BNST but not in tissue samples that included SCN or cortex. Preliminary results suggest that binding is strongest at the start site of transcription. Our findings therefore suggest that gonadal hormones influence VP expression in the BNST directly, by transactivation of the VP gene through ERα.