Atrial natriuretic peptide (ANP) concentarions were determined in 20 women: 10 women with premenstrual tension syndrome (PMS) and 10 comparable asymptomatic women. The asyptomatic women showed significant decrease while the PMS group showed insignificant change in mean ANP concentration in the midluteal phase compared to the level in the follicular phase. The mean midluteal ANP concentration was found to be significantly higher in the PMS group (P < 0.05). Mean plasma aldosterone concentration was found to increase significantly in the luteal phase in both goups with lower rise in the control group. No significant difference wa noted in both groups regarding serum estradiol and progesterone in both follicular and luteal phases.