It has been reported that there is a fast action of estrogen on the target cells and our previous work has also proved that estrogen may induce intracellular calcium to increase rapidly in dormant mouse blastocyts.But the membrane receptor of estrogen is not clear.Recent researches on some kinds of cells have suggested that G protein-coupled receptor 30 (GPR30) is involved in the rapid effects of estrogen as its membrane receptor.In this research, we used cell biology, immunology biochemistry, molecular biology and confocal microscopy to explore whether GPR30 expressed on the mouse early embryos and its role in the fast action of estrogen on blastocysts.Our results showed that GPR30 expressed from the two cell stage of embryos to the blastocyst and its location is consistent with the binding sites of estrogen on the cell membrane of the blastocyts.A special agonist for GPR30(G1) also induce the rapid increase of intracellular calcium in dormant mouse blastocyts, while a special antagonist for GPR30 (G15) can inhibit the fast effect of estrogen.Thus, the fast effect of estrogen on blastocysts may be mediated by GPR30.