Because of the unique combination of physical (e.g. bloating, water retention) and psychological (e.g. mood, memory) symptoms associated with premenstrual syndrome (PMS), various hypothalamic and pituitary hormones have been implicated in the pathophysiology of PMS. We measured plasma adrenocorticotropic hormone (ACTH), arginine vasopressin (AVP) and atrial natriuretic peptide (ANP) across the menstrual cycle in 19 women with PMS and 12 normal women. AVP concentrations were lower throughout the menstrual cycle in symptomatic PMS patients compared with PMS patients during asymptomatic cycles and normal women. No differences in ACTH and ANP were observed between patients and controls. However, ACTH and ANP were positively and significantly correlated with each other in women with PMS but not in controls. These findings contribute to a growing list of menstrual cycle-independent findings in women with PMS and suggest that there may be an underlying neurobiological vulnerability that predisposes some women to experience somatic and mood dysregulation in the luteal phase of the menstrual cycle.