Though in slow freezing of blastocysts some post-thaw morphological predictors of pregnancy have been investigated, no such data have been published for vitrified and warmed blastocysts. Therefore, a prospective fourpart score was applied to vitrified/warmed blastocysts to evaluate if certain morphological parameters could act as predictors of implantation, pregnancy, and life birth. All blastocysts considered to be viable after warming were scored according to a previously unpublished grading system based on re-expansion, hatching (out of artificial gap in the zona pellucida), extensive cytoplasmic granulation and presence of necrotic foci. Overall, 74% of the vitrified blastocysts were found to be viable after warming. Early blastocysts showed better survival as compared to extended/hatching blastocysts (p<0.01). Out of the morphological parameteres analyzed, immediate re-expansion (p<0.05) and spontaneous hatching (p<0.001) were positive predictors of the rates of implantation, pregnancy and life birth. The opposite hold for exensive cytoplasmic granulation (p<0.05) which was negatively correlated. Accurate scoring of warmed blastocysts (within the first two hours) allows for prediction of pregnancy outcome and, thus, will help to further reduce the number of transferred embryos.