Gestational trophoblastic diseases comprise a rare spectrum of disorders in which the normal regulatory mechanisms controlling the behaviour of trophoblastic tissue are lost. They vary from the benign complete and partial hydatidiform moles to the frankly malignant choriocarcinoma and placental site trophoblastic tumours. The majority will be cured by suction curettage, followed by human chorionic gonadotrophin screening, but some will go on to need chemotherapy. The majority of patients will be cured even despite the presence of metastatic disease. Patients should have their treatment stratified according to various prognostic factors in order to ensure firstly their disease is eliminated and secondly to reduce the incidence of long-term treatment complications.