Choriocarcinoma and placental site trophoblastic tumor (PSTT) are rare varieties of gestational trophoblastic disease (GTD). PSTT alone constitutes about 1-2% of all trophoblastic tumors, which presents at early reproductive age and the serum beta-hCG level is much lower than choriocarcinoma. This tumor usually invades the myometrium and its depth of penetration is a prognostic factor. The first case report is regarding a 33-year-old woman with vaginal bleeding 3 months after abortion. The ultrasound exhibited heterogeneous and hypervascular mass related to previous cesarean scar. Serum beta-hCG level was 67 mIU/ml and chemotherapy was administered. However, due to severe vaginal bleeding and no regression in mass size, total abdominal hysterectomy was performed. Histopathological examination and IHC staining confirmed PSTT from previous cesarean section. The second case report is regarding a 33-year-old woman with cervicoisthmic choriocarcinoma, which was mistaken as cesarean scar pregnancy. The ultrasonography and elevated serum beta-hCG level suggested cesarean scar pregnancy. The patient was treated with methotrexate without any effect. Eventually, cervicoisthmic choriocarcinoma was detected after hysterectomy. A diagnostic error was made leading to possible uterus perforation along with incorrect chemotherapy that resulted in a life-threatening condition. It is concluded that PSTT and choriocarcinoma are the two important differential diagnoses of sustained elevated beta-hCG when imaging evidence is also suggestive. Although PSTT and cervicoisthmic choriocarcinoma are rare, they do exist and are on the rise.