Miscarriage is the most common complication of pregnancy, 80% of it occurs in the first 12 weeks. Approximately 20% of women attending early pregnancy units suffer a miscarriage. Most women will present with history of vaginal bleeding, abdominal pain both which are traditionally associated with miscarriage. However significant proportion of women will be asymptomatic. Transvaginal sonography is necessary to confirm complete evacuation of the uterus while using endometrial thickness is confusing. Patients – this study were thirty from Obstetric out patient clinic in Said Galal hospital in reproductive age using transvaginal ultrasonagraphy and histopathology for all production of curettage for all patients in this study. The aim of this work was to assess endometrial thickness in comparison to histopathological findings regarding retained products of conception. Results: there was a significant positive correlation between endometrial thickness and presence of retained products of conception. Conclusion: using a cut off 18mm endometrial thickness can be used to plan further management either operative or conservative.