AbstractCervico-isthmic pregnancies (CIP) are often complicated by massive hemorrhage due to placenta previa and adhesion. Herein, we present a case of CIP without placenta previa, complicated by cervical incompetency. A 39-year-old multiparous woman was diagnosed with CIP at 8 weeks. The placenta was located on the normal site, and no significant ultrasonographic findings were noted after 14 weeks. At 20 weeks, a cervical incompetency was complicated. A healthy infant was delivered by a cesarean hysterectomy at term. Histopathological examination confirmed CIP with placenta increta. In cases with CIP without placenta previa, the diagnosis during early gestation and careful evaluation of uterine cervix is essential to avoid severe complications.