present work was to determine the efficiency of in vitro bovine embryo production using oocytes collected from postmortem ovaries fertilized with frozen-thawed sperm obtained from either commercial or Murciano-levantina bulls. Cumulus-oocyte complexes were matured for 24h in TCM199 with 10% FBS, 2mM L-glutamine, 0.2mM sodium pyruvate, 0.3 µgmL −1 LH and 5 µgmL −1 FSH. Oocytes presumed matured were fertilized with Percoll-prepared sperm (750000/mL) in IVF-TALP, as described by Parrish et al., (1988 Biol. Reprod. 38, 1171–1180). Zygotes (at 18h) or two-cell-stage embryos (at 48h) were stained with Hoechst 33342 (10 µgmL −1 ; 20min) and assessed by means of epifluorescence microscopy.The experiment was replicated on 4 occasions.The results of penetration (PEN-%), average number of spermatozoa inside the oocyte (S/O), monospermy (MON-%), putative embryos (zygotes) with two pronuclei (2 PN-%) and percentages of cleavage at 48 hours were recorded (Table 1). The results show that early embryos can be obtained with no differences in monospermy and cleavage rates regardless whether the sperm source was commercial or Murciano-levantina (P ≥0.05). ∗ Lista Mundial de Vigilancia para la Diversidad de los Animales Domesticos (1997). http://www.fao.org/docrep/V8300S/V8300S00.htm.