Background: Missed Abortion is non-viable intrauterine pregnancy with either an empty gestational sac or a gestational sac contains an embryo without fetal heart activity.
Objectives: The aim of this study was to compare effect of misoprostol with clomiphene citrate, misoprostol with letrozole and misoprostol alone in terminating first trimester missed abortion.
Patients and methods: This randomized clinical trial was included patients with missed abortion attending to our outpatient clinic at South Valley University Hospital, Department of Obstetrics and Gynecology. Fifteen patients were excluded during the follow-up period; hence, 37 patients per group were included in the final analysis. They divided into three groups: Interventional group (A): received 5mg  letrozole ; Group (B): received 100 mg clomiphene citrate and Group (C): Control group received calcium carbonate . Then all patients received two doses of   800 microgram misoprostol orally. 
Results: As regard outcome among the three studied groups. The results showed that 21.6% cases in group (A) showed failure in management with six cases needed surgical evacuation and two cases completed treatment on misoprostol, 32.4% cases in group(B) showed failure in management with ten cases needed surgical evacuation and two cases completed treatment on misoprostol and 37.8% cases in group(C) showed failure in management with ten cases needed surgical evacuation and four cases completed treatment on misoprostol.
Conclusion: Letrozole pre-treatment with misoprostol increases efficacy of misoprostol in induction of complete abortion of non-viable first trimester pregnancy with no evident side effects.