Background: The variability in the duration of lactational amenorrhoea (LA) lead to develop statistical multivariate models to predict the risk of the appearance of the first postpartum menstruation. Aim To estimate the probability of recovering the first postpartum menstruation by means of a survival analysis, including hormonal levels and other parameters as predictor variables. Material and Methods: Eighty one mothers in exclusive breasfeeding until the sixth postpartum month, in whom estradiol, basal and post suckling prolactin were measured at the third post partum month, were studied. The variables that better predict the appearance of the fiist menstruation between the 3(rd) and 12(th) pospartum months, were identified using a Cox model survival analysis. Results. The median amenorrhea survival time (the lapse when the chance of recovering menstruation is 50016) was 209 days from delivery. Dichotomized estradiol and post suckling prolactin were the only significant variables that predicted the return of points of 190 pmol/ and 2,550 mIU/L, respectively. Conclusions: Post menstruation, with cutoff suckling prolantin and estradiol levels, measured at the third post partum month, are predictor for the time of appearance of the first postpartum menstruation (Rev Med Chile 2007; 135.- 419-26).