Objective: This study was devised to determine the value of sonographically detected subchorionic hematoma in the prediction of the outcomes of threatened abortion.Methods: Thirty-six cases of threatened abortion with subchorionic hematoma made up the study group and the control group consisted of 20 cases of threatened abortion. The patients were followed prospectively until 20 weeks of gestations.Results: The difference between the incidence of abortion in two groups was not significant (p=0.4955). In the stud/ group, there was not any significant difference in volumes of subchorionic hematoma between the cases resulting in abortion and the cases displaying a normal pregnancy course (p=0.1983). Relative volume of subchorionic hematoma (subchorionic hematoma volume/gestational sac volume) in the cases displaying a normal pregnancy course and those resulting in abortion was 20.83%+/-8.1% and 32.25%+/-8.8%, respectively, and this difference was found to be significant (p=0.0015).Conclusion: It is suggested that in the cases of threatened abortion neither the presence nor the volume of subchorionic hematoma was important in determining the prognosis of cases, though the relative volume of subchorionic hematoma was found to be a better prognostic parameter predicting the outcome of threatened abortions.