Study Design: Prospective randomized interventional study. Materials and Methods: 100 women with singleton pregnancy about 28-36 weeks, with isolated oligohydramnios [amniotic fluid index (AFI) < 5] were enrolled in the study. Before the proposed intervention, the antenatal risk factors were studied. Patients received 20 mg isosorbide mononitrate (IMN) vaginally. Patient were followed after 24 hours then weekly. The treatment was continued till the liquor improved significantly or until delivery. Outcome measures; mean increase in liquor, intervention delivery interval, and neonatal outcome were studied.