In vitro embryo culture is an important step of in vitro production of bovine embryos. The aim of this study was to compare the in vitro development of bovine embryos in G1.3/G2.3 sequential culture media and CR1aa culture medium. Oocytes were obtained from ovaries of slaughtered cows and matured in TCM-199 medium in humidified air containing 5% CO(2) at 39 degrees C. Matured oocytes were fertilized in vitro using frozen bull sperm prepared with Percoll separation. After fertilization, the presumptive zygotes were denuded from cumulus cells and randomly allotted for 2 treatments: Culture in CR1aa (n = 116) and G1.3/G2.3 (n = 125). The embryo culture was carried out in 50 mu L droplets of the media that were placed in incubator containing 6% CO(2) 5% O(2) and 89% N(2). The embryos were evaluated on days 3, 5 and 7 following in vitro fertilization. The difference of cleavage rates between 2 treatments was not found significant (p>0.05). However, significant difference was observed between 2 treatments at the level of the obtaining rate of morula and blastocyst (p<0.05). The results showed that G1.3/G2.3 sequential media significantly favoured developing of morula and blastocysts in comparison to CR1aa medium (32.0% versus 10.40% versus 18.96 and 2.58%, respectively).