In this study, we examined the effects of porcine granulocyte-macrophage colonystimulating factor (pGM-CSF) on in vitro development of porcine embryos produced by somatic cell nuclear transfer (SCNT) at first time. The objective of present study was to verify effects of pGM-CSF on SCNT-derived blastocyst formation and evaluate gene expressions and qualities of the blastocyst formed after pGM-CSF treatment. Data were analyzed with SPSS 17.0 using Duncan’s multiple range test. A total 522 cloned embryos in 6 replicates were treated with 10 ng/ml concentration of pGM-CSF during in vitro culture (IVC). It was demonstrated that treatment of 10 ng/ml pGM-CSF could increase blastocyst formation and total cell number in blastocyst significantly (p<0.05) compared to the control (12.3% and 41.4 vs. 9.0% and 34.7, respectively). However, there was no any effect on cleavage rate. It was found that the number of cells in the inner cell mass (ICM) and trophectoderm (TE) were significantly increased compared to the control (4.4 and 31.9, respectively) when cloned embryos were cultured with 10 ng/ml pGM-CSF (6.0 and 43.0, respectively). It was also found that treatment of 10 ng/ml pGM-CSF significantly (p<0.05) increased POU5F1 and Cdx2 mRNA expressions in blastocysts. In addition, Bcl-2 mRNA expression was found to be significantly (p< 0.05) up-regulated in blastocysts in the pGM-CSF supplemented group compared to the control. In conclusion, these results suggest that pGM-CSF may improve the quality and developmental viability of porcine cloned embryos by enhancing nuclear reprogramming via regulating transcription factors expression.