Gestational trophoblastic disease (GTD) is a term used for a group of pregnancy-related tumours, overwhelmingly affecting women of childbearing age. These tumours are rare, and they appear when trophoblastic cells start to grow out of control. In these conditions production of beta subunit of human chorionic gonadotropin (hCG) is evident. Hydatidiform moles, partial or complete, are in most cases benign featured by villous hydrps, scalloping effect, hyperplastic trophoblastic pseudoinclusions and syncytiotrophoblastic sprouts. Invasive mole is an aggressive trophoblastic lesion with myometrial and/or vascular invasion. Choriocarcinoma, placental site trophoblastic tumor and epitheloid trophoblastic tumor are clearly malignant tumors with proliferation of intermediate trophoblast, with metastatic potential. Tumor-like trophoblastic conditions are placental site nodul and exaggerated placental site wich are proliferative lesions and reactive processes and are not considered as true tumor lesions.In all of these conditions vaginal bleeding is the most common symptom followed by elevation of serum beta hCG. GTD has to be confirmed histologically with extensive sampling of the material. Follow up is necessary in all women with GTD and it is rutinley done by measurment of serum levels of hCG. Since GTDs are proliferative conditions of diferent trophoblastic tisues, pathologists should be well histologicly educated about normal pregnancy stages and its abnormalities in order of adeqate diagnosing these rare conditions.