Abstract: The objective of this study was to examine the telomerase activity in swamp buffalo oocytes and early embryos derived from in vitro fertilization (IVF). The telomerase activity of immature and matured oocytes, IVF embryos at the 2-4 , 8-16 cell, morula and blastocyst stages was assayed using a telomere repeat amplification protocol (TRAP). The telomerase activity was higher in the immature oocytes than that in the matured oocytes (P< 0.05). After in vitro fertilization, the telomerase activity decreased as the zygotes cleaved to the 2-4 cell and 8-16 cell stages, increased again when the embryos developed to the morula stage (P< 0.05), and reached the highest level at the blastocyst stage. When the telomerase activity was calculated on the individual cell, telomerase activity declined gradually as the immature oocytes matured to Metaphase II and developed to the blastocyst stage after in vitro fertilization. These results indicate that the changes of telomerase activity in the buffalo oocytes and early embryos are related to their maturation, embryonic developmental block and totipotency decline during the embryogenesis.