Background: Recurrent pregnancy loss (RPL) related to the presence of two or more clinically recognized consecutive pregnancies before the 20th week of gestation (glacial, molar and biochemical pregnancies are not included). It can be primary or secondary. 0.4-1% of women experience three consecutive miscarriages. Aim of the work:To evaluate the Doppler parameters (Resistance Index and Pulsatility index) in the uterine arteries of non-pregnant women with recurrent miscarriage. Patients and methods: This study conducted on 40 non pregnant women complaining of unexplained recurrent pregnancy loss, from those patients attending gynecology clinic of Al -Azhar university outpatient clinic in Assuit. Patients were classified into: IMN group: (20 patient) complaining of unexplained RPL receiving isosorbide mononitrate vaginally (IMN) 20 mg tablet Placebo group: (20 patient) complaining of unexplained RPL receiving placebo. Results: Our results revealed that standard deviation ratio, pulsatility index (PI) and resistance index (RI) of the uterine-artery had fallen in IMN group with no significance difference in placebo group. Conclusion: Isosorbide mononitrate as a nitric oxide donor can be improved Doppler indices, so may be an important drug in treatment of cases of unexplained RPL.