ABSTRACT Nowadays , thrombophilia is one of the leading causes of RPL which has negative side effects due to psychological effect and the high expenses of investigations and attempts to get normal full term pregnancy up to ICSI trials in some cases. So as early as possible we try to diagnose the cause of abortion and treat it to avoid another bad experience of abortion. Aim of the work: to evaluate the correlation of factor V Leiden and MTHFR C677T gene mutation in primigravida late first trimester abortion and to identify candidates for anticoagulation therapy to improve pregnancy outcome .METHODOLOGY: polymerase chain reaction (PCR) and reverse-hybridization were used to assess MTHFR and FV leiden mutations . Results: MTHFR C 677T mutations were 42.5 %. While factor V leiden gene mutation were 20%. Combined MTHFR C 677T mutations and factor V leiden was 10 %, normal cases were 27.5%. The cases without MTHFR C 677Tgene mutations were 47.5% . While The cases with MTHFR C 677T mutations were 52.5%. Heterozygous MTHFR C 677T mutations cases were 37.5 % , homozygous cases were 15% .The cases without Factor V Leiden gene mutations were 70 %, cases with Factor V Leiden mutations were 30%. All cases with Factor V Leiden mutations were heterozygous and there was no homozygous cases. Conclusion: MTHFR mutation is highly expected in late first trimester missed abortions in primigravida specially the heterotype so significantly affect the pregnancy adversely while FACTOR V LEIDEN mutation is less likely to be found.