Pregnancy complications are still a challenge for physicians, because knowledge of pathomechanisms and prophylactic measures is still limited. In recent years thrombophilia as a risk factor for pregnancy complications has gained much attention in the scientific community. However, data on this topic in the literature are conflicting. Besides an established association between antiphospholipid antibodies and pregnancy loss, available data suggest additional associations for antithrombin deficiency, hyperhomocysteinemia and also for factor (F)V Leiden, prothrombin G20210A variation, and protein S-deficiency. The contribution of thrombophilia to the risk of pre-eclampsia is less well established and recent studies did not confirm earlier data suggesting an association between thrombophilia and pre-eclampsia. A limited number of prospective studies have failed to reveal an increased risk of pregnancy complications in unselected women with thrombosis risk factors. Low-molecular weight heparin (LMWH) seems to have a positive effect on pregnancy outcome after single or recurrent abortions, however, data from only one controlled trial are available. Experience in the prevention of pre-eclampsia by prophylactic heparin is very limited, and in addition, data on pregnancy complications in women with known heritable thrombophilia or a history of thrombosis are inconsistent. These women will usually have a favorable pregnancy outcome referring to the European Prospective Cohort on Thrombophilia Study. In conclusion, thrombophilia screening might be justified in women with pregnancy loss and treatment with LMWH might be considered in those with pregnancy loss and thrombophilia. Further prospective studies and controlled interventional trials are urgently needed.