A large body of evidence obtained during the past 6 years suggests a significant role for inherited thrombophilia in the development of gestational vascular complications. While the majority of women with thrombophilia will have an uneventful gestation, case-control studies have demonstrated that thrombophilia is more prevalent in cohorts of women with pregnancy loss early onset preeclampsia, placental abruption, and severe intrauterine growth retardation (IUGR). Placental pathological findings in women with thrombophilia are hallmarked by thrombosis and fibrin deposition potentially to a greater degree than in normal pregnancy. Preliminary case-control studies suggest a benefit for prophylaxis with low molecular weight heparins (LMWH), and prospective randomized trials are in progress to define whether LMWH are effective in preventing pregnancy loss in women with thrombophilia and previous fetal wastage.