[en] Murine placentation is associated with the invasion of maternal endometrium by trophoblasts and an extensive maternal and foetal angiogenesis. Plasminogen activator inhibitor-1 (PAI-1) is transiently produced by spongiotrophoblasts and trophoblast giant cells at 10.5-11.5 day post-coitum (dpc). Knowing the key contribution of PAI-1 in the regulation of angiogenesis, we have now analyzed the consequence of PAI-1 deficiency on murine placentation. Morphological and quantitative computer-assisted image analysis revealed abnormal placental morphology in PAI-1 (-/-) mice at 10.5 and 12.5 dpc. At 10.5 dpc, the genetic ablation of PAI-1 resulted in a transient reduction of both maternal and foetal vascularizations in the placenta and increased trophoblast cell density. This was associated with a poorer development of the labyrinth and an extension of the decidua. A larger spongiotrophoblast layer appeared at 12.5 dpc in PAI-1 deficient mice. Placental morphology was normalized at 14,5 dpc. Microarray analyses performed on laser capture microdissected labyrinths revealed that 46 genes were differentially expressed at 10.5 dpc between the two genotypes. However, only 11 genes were still differently modulated at 14.5 dpc when normalization of placental morphology had take place. This transcriptomic profiling highlighted a dysregulation in the expression of placenta-related cathepsin family members. All together our data provide evidence for a transient impaired placental morphology in PAI-1-deficient mice which is then normalized leading to normal embryonic development.