Seven Egyptian buffaloes were used to study the plasma changes of inhibin, FSH, estradiol-17b and progesterone concentrations during the at estrous cycle. These hormones were determined at estrous and two interval until day twenty two of estrous cycle. Plasma inhibin estimated by enzyme-linked immunoasorbent assay (ELISA). Both FSH, estradiol-17β and progesterone were estimated by radioimmunoassay (RIA). In order to elucidiate the feedback system controlling mentioned hormones during estrous cycle, variations in the levels of hormones and their inter-relationshpis were studied. Plasma inhibin levels ranged between 439.28 and 584 pg/ml during various stages of estrous cycle, peak of inhibin level was at day of estrous by an average of 584 pg/ml. Follicle stimulating hormone levels were higher at day of estrous (25.48 ng/ml), decreased and fluctuated towards end of estrous cycle and then increased at twenty two days of estrous cycle. Peak of estradiol-17β was 18.54 pg/ml at day of estrous, while the peak of progesterone was 4.39  ng/ml at twelfth day from the start of estrous. It could be concluded that each of inhibin and estradiol-17b seems to have a feedback regulatory effect on FSH secretion in buffaloes. Key words: Inhibin, FSH, estradiol-17b, progesterone, estrous cycle, buffalo.