In contrast to a previous report by Krussel et al., with the inclusion of larger numbers of unfertilized oocytes and normal embryos and more sensitive immunofluorescence, this study shows that expression of vascular endothelial growth factor messenger ribonucleic acid can be detected from the oocyte to the blastocyst stage and that protein can be detected from the 3-cell stage to the blastocyst stage in human preimplantation embryos.