This study was conducted to reconstruct heterogeneous embryos using equine skin fibroblast cells as donor karyoplasts and the bovine oocytes as recipient cytoplast for investigating the reprogramming of equine somatic cell nuclear in bovine oocyte cytoplasm and the developmental potential of the reconstructed embryos. Adult horse skin fibroblast cells serum-starved were used as donor somatic cells. Bovine oocytes matured in vitro were employed as recipient cytoplasts. The fusion of fibroblast cells into recipient cytoplasm was induced by electofusion. The fused eggs were activated by inomycin with 2 mm/ml 6-dimethylaminopurine (6-DMAP). The activated reconstructed embryos were co-cultured with bovine cumulus cells in synthetic oviduct fluid supplemented with amino acid (SOFaa) and 10% fetal calf serum (FCS) for 168 h. The results showed that the first completed cleavage of xenonuclear transfer equine embryos occurred between 30 and 48 h following activation. 52% of the injected oocytes were successfully fused, 72% of the fused eggs underwent the first egg cleavage and 17% of the heterospecific nuclear-transferred zygotes developed to 4- or 8-cell embryo stages. This study demonstrated that the reconstructed embryos have undergone the first embryonic division and the reprogramming of equine fibroblast nuclei can be initiated in bovine-enucleated oocytes.