Conflicting data still exist regarding the extent of paternal pronuclear DNA demethylaton in one cell-stage mammalian embryos. We have used and compared two in vitro techniques commonly used for in vitro embryo production and then we evaluated the extent of labelling in both these groups after 5-methylcytosine or dimethyl H3/K9 labelling. We have found that there is no differences in the methylation pattern between both those techniques. Our results indicate that the inconsistency in methylation pattern probably resulted from insufficient cytoplasmic maturation of oocytes then from the in vitro technique used for embryo production.