Inherited thrombophilia may cause important complications in pregnancies including maternal death, early and late pregnancy loss, preeclempsia, intrauterine growth restriction and placental abruption. This study was developed to investigate the fetal loss and successful birth rates in hereditary thrombophilic patients treated with low-dose acetylsalicylic acid and low molecular weight heparin to determine the necessity and effectiveness of this treatment. Ninety-three patients with the history of recurrent pregnancy loss or thromboembolism were included in this study. Eighty milligram acetylsalicylic acid treatment was started just after the diagnosis for the patients with hereditary thrombophilia, continued throughout pregnancy and ceased 3 days before the delivery. Low molecular weight heparin (LMWH) was started for the patients with the unsuccessful in-vitro fertilization (IVF) history, just after finishing the egg collection. For the other patients, LMWH was started after the positive result of the pregnancy test. Treatment was started for 67 (72%) of patients. Among the treated 67 patients, 38 had MTHFR C677T gene mutation, 25 had protein S deficiency, 19 had FV Leiden mutation, four had protein C deficiency, two had Prothrombin 20210A gene abnormality, two had antiphospholipid anticore syndrome and two had AT III deficiency. Fifty-seven (85.1%) of 67 patients under treatment had pregnancy. Forty-one (61.2%) of those 57 patients had a live birth, whereas 16 (23.9%) of them had abortus under treatment. In regression analysis, only protein C and S deficiencies were found to be independent risk factors. In conclusion, inherited thrombophilia should always be kept in mind as an etiological factor of recurrent abortus. With treatment, success rates are between 60 and 80%. Severe side effects due to treatment are rare. But randomized, double-blind, placebo-controlled studies are still necessary to evaluate the benefit of heparin and acetylsalicylic acid treatment in women with the history of inherited thrombophilia. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.