Present experiment was couducted to clone swamp bufalo and cattle embryos using i vitro matured swamp buffalo oocytes as recipient cytoplasts and swamp buffalo and cattle ear fibroblast cels (BEFC and CEFC) as door nuclei and examine the use of mouse fetal fibroblast cell as co-culture cell during embryos evelopment. Swamp buffalo ovaries were collected from slaughterhouse and cumulus oocyte complexes (COCs) were harvested by aspiration and then in vitro matured for 19-20 h. Matured oocytes were enucleatd by micromanipulation under an inverted microscope. Enucleation was confirmed by staiing the removed portion with Hoechst 33342. Individual donor cells of swamp buffalo or cattle ear fibroblast cells (diameter 14-16 micro m) were inserted into perivitelling space of reciient cytoplasts by micromanipulation. The couplets were fused with two DC pulses of 30 V/couplet for 15 micro sec each time in fusion medium. After fusion, reconstructed embryos were immediately activated with A23187 followed by culturing in SOFaa-10 which containing cycloheximide and cytochalasin D for 5 h, then cultured in SOFaa supplemented with 1 percent FCS (SOFaa-1) for 2 days. The embryos at 8-cell stage were harvested and assigned to co-cultured wit frozen-thawed buffalo oviductal epithelial cell (BOEC) or mouse embryonic fibroblast cell (MEFC) for another 2 days then replaced twice with SOFaa-10 every 2 days. The result from the experiment demonstrated that the embryos reconstructed by both BEFC and CEFC could developed nearly the same rate to 8 cell (53.1 vs 51.0 percent), morula (19.8 vs 17.0 percent), and blastocyst stage (15.6 vs 13.9 percent) when co-culture with BOEC. While MEFC could support the recostructed embryos developed to morula at the same rate (10.8 percent) and very low rate to blastocyst stage (2.8 vs. 1.3 percent). The cloned cattle embryos could be produced using swamp buffalo oocytes as recipient cytoplasts and co-culture with MEFC could support the development but not as good as BOEC. The development of the cloned cattle embryos in the recipiet cows will be further studied.