In vitro embryo production (IVEP) is concerned as one of the most important aspects of modern science. IVEP is a beneficial and valuable method for economical production of animal. Oocytes retrieved from ovine ovaries that are used to IVEP, are heterogeneous in terms of quality and developmental competence. Because the poor quality of the oocyte at the onset of maturation, IVEP is inefficient. Oocytes retrieved of ovaries are heterogeneous population of both growing oocytes (BCB-) and fully grown oocytes (BCB +). In this heterogeneous population, there is a delay in the maturation of oocytes which may be because of the BCB-oocytes in this population, so that this type of oocytes have an asynchronization between cytoplasmic and nuclear maturation. Therefore, the developmental capacity of BCB- oocytes is lower than BCB+ oocytes. In addition, the pre- maturation culture (PMC) oocyte before oocyte maturation has been suggested to improve development of oocyte. Second messenger cyclic adenosine mono-phosphate (cAMP) has been proven (cAMP) plays an essential role in the induction of meiotic arrest and the phosphodiesterase type 3 enzyme in oocytes and adenylyl cyclase enzyme in cumulus cells by degrading and synthesis cAMP, result in decrease and increase respectively the level of the second messenger in the oocyte. Thus, the use of inhibitors of phosphodiesterase type 3 and activator of adenylate cyclase can increase the level of cAMP in the oocyte and thus induce meiotic arrest. Therefore, the aim of this study was to evaluate the effect of cilostamide (an inhibitor of PDE3) and / or Forskolin (an activator of adenylate cyclase) on meiotic arrest and developmental rate ovine BCB-oocytes were isolated by BCB test. Accordingly, a two-step culture system consisting of 6, 8, 10 and 22 hours of culture in the presence of 1 µM cilostamide and / or 50 µM Forskolin, followed by 22 h of culture in maturation medium was designed. The results showed that during the 6 hours PMC, Forskolin significantly meiotic arrest BCB- oocytes at GV stage increased (P 0.05) and then cilostamide and the combination of these two drugs was better effect. Moreover, Forskolin significantly increased the rate and quality of blastocysts derived from ovine BCB- oocytes (P 0.05). Therefore, it was concluded that a two-step culture system may improve the developmental competence of in vitro ovine BCB- oocytes. Keywords : Ovine, two-step culture, PMC, BCB test, embryonic development