In healthy women, plasma norepinephrine (NE) has a cycle with the highest levels occurring at ovulation and early luteal phase. We examined plasma NE cyclicity in premenstrual syndrome (PMS) patients as compared to controls, its relation to estradiol (E₂), progesterone (P), luteinizing hormone and follicle-stimulating hormone, and the correlation of these parameters with the PMS symptoms. Lack of NE cyclicity was observed in PMS patients. In controls, peak NE levels occurred at ovulation and early luteal phase. In PMS, serum E₂ was higher during the follicular phase, while P and gonadotrophins were higher especially at ovulation and the luteal phase. In the late luteal phase, E₂ levels were lower in PMS patients than in controls. A negative correlation was observed between the area under the curve for E₂ in the luteal phase and PMS somatic and mental scores. Plasma NE showed a negative correlation with abrupt mood swings, impatience, nervousness, tiredness, weakness, apathy, and headache. These data suggest that lack of NE cyclicity characterizes PMS, some symptoms being related to low E₂ levels during the late luteal phase and decreased noradrenergic activity at ovulation and the luteal phase.