Background: Cervical ripening is essential to ensure an uneventful surgical evacuation of uterine cavity. Misoprostol is a wellestablished cervical ripening agent with documented adverse effects. Isosorbide mononitrate (ISMN), a nitric oxide donor appears to emerge as a potential cervical ripening agent with lesser adverse effects. Methods: A prospective randomized controlled trial was conducted on 120 patients with 60 patients in group – A and 60 in group – B. 400µg Misoprostol and 40mg ISMN were placed per vaginally at zero hour in group A and B respectively. The dose was repeated every three hours (upto a maximum of 4 doses) after a cervical assessment. Cervical ripening was evaluated using Hegars dilators. The number of dilator which could be easily negotiated and time required to easily negotiate a No.10 or larger dilator was assessed. Intraoperative blood loss was assessed. Adverse effects were noted using a symptom questionnaire. Results: Time required for cervical ripening was significantly lesser (P <0.0001) in group A than in group B (8.63 hrs vs. 10.52hrs). At every assessment women with misoprostol showed higher extent of ripening, 3hrs – 3.4±0.19 vs. 2.6±0.29 (P >< 0.0001), 6 hrs - 5.2±0.76 vs. 4.3±0.65 (P < 0.0001), 9 hrs – 8.2±1.56 vs. 7.3±1.48 (P – 0.02), 12 hrs - 11.9±1.89 vs. 9.9±1.48 (P – 0.008). Intraoperative blood loss was significantly higher in women primed with ISMN (89.9±41.41ml vs. 63.4±27.68ml) with a P value of < 0.0001. Adverse effects are seen more with the use of Misoprostol. Conclusion: Misoprostol appears to cause quick cervical ripening with adverse symptoms whereas ISMN appears to cause slower ripening with lesser adverse effects. Misoprostol appears to be a better drug in emergencies when quick evacuation is required or blood loss has to be minimized. ISMN appears to be a better drug in stable patients with haemodynamic stability.