We can now detect molar pregnancy at a much earlier gestational age than before by using high resolution vaginal ultrasonography. As a result, the current clinical presentation of complete hydatidiform moles has clearly changed compared to that of the classic type of mole. The diagnosis of molar pregnancy is nearly always made by ultrasonography. Ultrasonography does not, however, always lead to diagnosis in the very early stages of gestation, before the chorionic villi have attained the characteristic vesicular pattern. Therefore, a histopathological examination of the products of conception should be required in all such cases. Hydatidiform moles should be treated by evacuating the uterus surgically as soon as possible after diagnosis. The patients must be followed up until their serial weekly serum human chorionic gonadotrophin (hCG) titre has fallen to an undetectable level.