OBJECTIVE: To characterize the pulsatile secretions of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin (PRL) during the menstrual cycle and to statistically evaluate their secretory concomitance. DESIGN: Pulsatility study performed during the midfollicular and midluteal phases of a same menstrual cycle, blood samples being collected every 10 minutes for 6 hours. SETTING: Participants investigated in the Division of Endocrinology, University Hospital. PARTICIPANTS: Nine healthy women (22 to 38 years) with regular menstrual cycles. MAIN OUTCOME MEASURES: Plasma LH, FSH, and PRL values were analyzed as raw and deconvoluted data, and the specific (nonrandom) secretory concomitance was evaluated statistically. RESULTS: The pulsatile secretion of LH was confirmed, and that of FSH and PRL was clearly established during both phases of the cycle by characterization of peak frequency, period, and amplitude. A specific secretory concomitance was assessed between LH and FSH in the follicular but not the luteal phase, and a tight concomitance between LH and PRL was demonstrated during both phases. CONCLUSIONS: These results are supportive of significant pulsatile secretions of the three hormones during the menstrual cycle, and they are demonstrative of a definite copulsatility of these hormones, suggestive of common regulatory factors in the complex temporal patterns of gonadotropin and PRL secretions along the cycle.