The effect of estradiol (E2) and progesterone (P4) on the IgA system, both at the systemic and at the mucosal level, was studied in 10 healthy young adult Mexican women during two consecutive menstrual cycles (MC); the control group consisted of five young adult Mexican men. Eight matched samples of blood and parotid saliva were obtained, in which serum E2, P4, and IgA were quantified. Parotid saliva was obtained with Curby's device and sIgA was quantified by an ELISA method. The MC was divided into follicular phase (FP, days 1 to 16) and luteal phase (LP, days 17 to 30). Serum IgA showed slight fluctuations along the period of study, but they were not different between women and men. Irrespective of the phase of the MC, salivary sIgA was higher in women than in men (P<0.01); sIgA was slightly but not significantly higher in the FP, as compared to the LP. The comparison of phases in each individual woman showed significantly higher levels in the FP (P<0.01). The profile of sIgA in saliva observed in women resembled the pattern of serum E2 (r = 0.859, P<0.05), suggesting a possible relation of E2 in the secretion of sIgA by the parotid gland.