Background: Pregnancy loss is the interruption and/or termination of pregnancy, either spontaneously or intentionally, before the fetus develops sufficiently to survive. About 80% of abortions occur in the first 12 weeks of pregnancy. Objective: To determine the accuracy of U/S parameters in predicting early pregnancy failure in pregnant with history of 1^st trimesteric recurrent pregnancy loss. Patients and methods: This was a prospective study that included 120 pregnant females with history of first trimesteric recurrent pregnancy loss. It was conducted in Obstetrics and Gynecology Department, Menoufia University Hospitals, and Rashid General Hospital, Al-Bahira, Egypt during the period from April 2019 until August 2020. Results: There is no significant difference between miscarriage group and ongoing pregnancy group regarding risk factors and demographic data (p > 0.05). In addition, crown-rump length (CRL) below 5^th percentile for gestational age (GA) category more significantly prevalent in the miscarriage group compared to the ongoing pregnancy group. While, mean gestational sac diameter (MGSD) below 5^th percentile for GA, caudal displacement of gestational sac (GS) or irregular GS could predict subsequent miscarriage. Embryonic heart rate/Fetal heart rate (EHR/FHR) below 5^th percentile for GA was statistically significantly more prevalent in the miscarriage group than in ongoing pregnancy group. Abnormally large YSD (> 95^th percentile for GA), absent yolk sac (YS), floating YS, deformed, irregular or hypo-echoic YS could predict subsequent miscarriage. Uterine artery resistance index (RI), pulsatile index (PI) and systolic/diastolic (S/D) ratio did not differ significantly between the miscarriage group compared to the ongoing pregnancy group across the various gestational ages. Conclusion: 1^st trimester U/S parameters are useful diagnostic tool to prognosis pregnancy outcome among patients with history of recurrent 1st trimester pregnancy loss.