Gestational trophoblastic disease (GTD) is classified as a metastatic or non-metastatic lesion, furthermore, villous GTD is distinguished from non-villous GTD. Because of their higher incidence and their risk of persistent gestational trophoblastic neoplasia (pGTN), early diagnosis of molar pregnancies is of clinical importance. Advances in ultrasound (US) technology and frequent application of transvaginal sonography in early pregnancy have changed the clinical and pathological presentation of molar pregnancies. Based on US imaging and histopathological examination of products of conception, the majority of cases are diagnosed in early pregnancy, either as incidental findings or in women presenting with symptoms of miscarriage. Molar pregnancies have characteristic sonographic features which are more pronounced as pregnancy advances. In early pregnancy, overall US detection rates for molar pregnancies range between 34-56% depending on gestational age, sonographic features, histologic morphology, apparative equipment, and operator expertise. There also seems to be an intrinsic limit to US detection rates based on histomorphometric features of the hydropic villi. Thus, in early pregnancy, lack of typical sonographic features does not exclude molar pregnancy. If a condition predisposing for pGTN is not recognized at the time of evacuation, prognosis is worse. With increasing demand for medical management of miscarriages and abortions, when products of conception are usually not submitted for histological examination, sonographic assessment of the chorion is mandatory. In the case of suspicious findings, surgical management and histological examination are indicated.