The paucity of biological material has inhibited identifying genes that are differentially expressed during mammalian oogenesis and preimplantation development. We report here the linear amplification of mRNA from small numbers of mouse oocytes and preimplantation embryos to generate amounts of sense RNA that are sufficient for suppression subtractive hybridization. The resulting oocyte-specific and 8-cell-specific cDNA libraries were partially characterized, and the known oocyte-specific ZP1, ZP2, GDF-9, BMP15, and H1_oo genes were found in the oocyte-specific cDNA library but not in the 8-cell-specific library. Further characterization of the subtracted oocyte and 8-cell embryo cDNA libraries should furnish a trove of information regarding temporal changes in gene expression during oogenesis and preimplantation development in the mouse.