Embryo production via in vitro fertilization and nuclear transfer has been accomplished in the dog, and the transfer of the cloned embryos has recently resulted in the birth of puppies. However, the efficiency of these technologies is still very limited. Until now, only two morulas and single blactocyst have been achieved in vitro. Therefore, the aim of the present study was to examine the effects of two different media (mSOF and TCM 199) on in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC) of immature dog oocytes. The study was performed in two steps. At the first step, the effects of two different media, on IVM of dog oocytes were investigated. At the end of the IVM period, the nuclear maturation rates were evaluated by aceto-orcein staining method. At the second step, after the IVM period the oocytes inseminated with fresh spermatozoa for 24 h and left for IVC for 7 d. At the end of the IVC period, embryonic development was assessed by microscopic observation at 24 h intervals and then fixed and stained by the same method. Consequently, maturation rates of oocytes in mSOF medium were significantly higher than those of the TCM 199 (P<0.001). After 7 d of the IVC period, only one oocyte was cleaved in the TCM 199. while eight oocytes cleaved and one of them developed to morula stage in mSOF medium group (P=0.037).