Maternal hypoxia induced by a variety of exogenous oxidative stresses such as ethanol intake, diabetes, and cigarette during pregnancy provokes the impaired embryonic gene expression and developmental malformations. We investigated the gene expression patterns of the representative selenium containing antioxidant enzymes (selenoproteins) such as cytosolic GPx (cGPx), gestrointestinal GPx (GI-GPx), plasma GPx (pGPx), phospholipid hydroperoxide GPx (PHGPx), and selenoprotein P (SePP) in the cultured mouse embryos under normal or hypoxic (low oxygen state, 5% O₂) condition at embryonic day 8.5 for 2 days using real-time PCR analysis. cGPx, pGPx, and SePP mRNAs were significantly decreased, but GI-GPx and PHGPx mRNAs were remarkably increased in the hypoxic state compared to normal gassing state (p<0.05). These findings indicate that hypoxic condition leads to the unusual expressions of selenoproteins during mouse organogenesis.