Heterotopic pregnancy is a simultaneous intrauterine and ectopic pregnancy. We report a case of a spontaneous ovarian heterotopic pregnancy. A 36-year-old woman, gravida 7 para 4-1-1-5 at 4 weeks gestation (spontaneous conception), presented to the emergency department with vaginal spotting, lower abdominal cramps with human chorionic gonadotropin(hCG) 10 772 mIU/mL (hCG at T0). Abdominal and pelvic examinations were benign. Transvaginal sonogram (TVS) showed an intrauterine gestational sac and yolk sac, no fetal pole visualised. She was discharged home with a diagnosis of threatened abortion. The patient returned to the emergency department 3 weeks later (T1) at 7 weeks gestation with recurrent vaginal bleeding and lower abdominal pain. Her TVS showed an empty uterus with small amount of free fluid in the cul-de-sac. A small 2 cm round mass noted in the adnexa with hCG of 4663 mIU/mL (hCG at T1). Laparoscopy revealed normal fallopian tubes bilaterally and a ruptured right ovarian ectopic pregnancy. Pathology was consistent with ectopic pregnancy. Abnormal hCG patterns should raise suspicion for heterotopic pregnancy.