The study was conducted on eighteen postpartum silent oestrus Surti buffaloes to evaluate the efficacy of Norgestomet ear implants alone and in combination with PGF2α. The buffaloes in Group-I & Group-II were implanted with Crestar for 9 days along with 2 ml injection of Crestar solution given on the day of implant insertion. In Group-II, additionally 500 μg Cloprostenol was given on one day before implant removal. Whereas, the buffaloes in Group-III served as silent oestrus control group and 5 ml normal Saline was given on 0 day and on 8th day as a placebo treatment. In the Norgestomet treated groups the significant decreasing trend of endogenous progesterone (P4) concentration observed at different time intervals of ear implant inserted followed by Norgestomet injection given treatment groups of animals. Oestradiol-17β levels of the blood serum did not show any significant difference (p >0.05) at 0 day, 5th day within the Group-I, Group-II & Group-III. But the mean values of Oestradiol-17β markedly increased thereafter at 10th day and on the day of estrus in the Group-I, Group-II & Group-III and showed significant difference (p <0.05) during that various time interval within that groups and also reflected the same picture in the overall mean value of serum Oestradiol-17β at different time intervals. Drastic increasing level of Oestradiol-17β might have influenced the earlier follicular activity followed by early estrus in the treatment groups, while steady increase in Oestradiol-17β in control group might have showed late follicular activity in that group lead to late estrus. 1427620266.php