Loss of pregnancy is a distressing problem for both the patient and the physician. Approximately 20% of pregnant women have symptoms of threatened abortion in the first trimester of pregnancy, and approximately half of these ultimately have a miscarriage.The advent of high-resolution transvaginal ultrasound (TVS) has revolutionized our understanding of the pathophysiology of early pregnancy failure. Moreover, many serum markers have been investigated in attempts to predict the outcome of pregnancy in the first trimester, with varying degrees of success.This has directed our attention to undergo this study on 160 women attended the outpatient clinic and the casualty unit of the Obstetric department in Kasr El Eini hospital; 80 women with clinical diagnosis of threatened abortion and 80 controls. All the patients undergone ultrasonpgraphic assessment of the uteroplacental circultion and the corpus luteum, in addition to measurement of maternal serum CA-125 level.Several studies including the present study concluded that serum CA-125 level determination is valuable in the women with symptoms of threatened abortion and it may be a cheap, sensitive and specific method in prediction of the cases of threatened abortion. Also, the study showed that there is a correlation between absence or decreased volume of the Corpus luteum on ultrasound examination and increased probability of early pregnancy loss while transvaginal color Doppler indices (pulsitility index) and (peak systolic velocity) are not helpful for predicting pregnancy outcome in these cases.