Objective: The present work aimed to study the effect of progesterone (CIDR)-based GnRH treatments plus eCG (1000 or 500 IU) on inducing and synchronizing the onset of puberty in buffalo-heifers. Methods: Buffalo-heifers (n=28) were randomly allocated into four treatment protocols (7 each): (G1, CIDR- eCG1000- GnRH), (G2, CIDR- eCG 500- GnRH), (G3, CIDR-GnRH) and (G4, CIDR- alone). The largest follicle diameter (LFD) and antral follicles counts (AFC) of small (≤ 4mm), medium (> 4mm- ≤8mm) and large follicles (>8mm) were estimated by transrectal ultrasonography on Days 0, 8, and 11. Also, the LFD was estimated on Day 13 as well. Results: On Day 11, the AFC of both small and medium-sized follicles was higher in G1 compared with G2 (P < 0.05) and with both G3 and G4 (P < 0.01). The AFC of large follicles was the greatest (P < 0.05) in G1compared with all groups but did not differ among G2, G3, and G4 on Day 11. On Day 13, the LFD showed non-significant variation between G1 and G2 as well as between G3 and G4. It showed a significant increase in G1 (P < 0.01) and G2 (P < 0.05) compared with either G3 or G4. The conception rate was the highest (P<0.05) in G1 compared with all groups. Conclusion: It could be concluded that the incorporation of eCG at a dose of 1000 IU in P4 (CIDR) based together with GnRH treatment protocol induces and synchronizes puberty in buffalo-heifers at the age of puberty.