Interstitial pregnancies comprise only 2%−4% of ectopic pregnancies (1). They are more dangerous because the rupture of interstitial pregnancies often results in massive hemorrhage or even shock. Recently there has been a trend to treat ectopic pregnancies, including interstitial pregnancies, with methotrexate injection. It is generally believed that methotrexate should only be offered to hemodynamically stable and unruptured cases. Here we report the first case of ruptured interstitial pregnancy successfully treated using a combination of methotrexate, electrocauterization, and vasopressin injection. A 29-year-old nulliparous woman came to our emergency service because of acute abdominal pain, which she had suffered for 1 day. She had a history of right tubal pregnancy and underwent right salpingectomy 1 year ago. Her last menstruation was 44 days ago. On examination, she was alert but pale; blood pressure was 83/33; pulse, 106; respiration, 20. Her abdomen was distended and rigid, with marked direct and rebounding tenderness. A urine pregnancy test was positive and her serum β-hCG level was 3256 mIU/mL. Ultrasound revealed massive ascites with no gestational sac visible intrauterine. Culdocentesis gave non-clotting blood. Under the impression of ruptured ectopic pregnancy, she received a blood transfusion and an emergency laparoscopy was arranged. During the operation, a 2-cm ruptured bulging mass with slow oozing of blood was seen at the right cornu of the uterus. Interstitial pregnancy was impressed, and 50 mg of methotrexate was injected into the bulging mass. Kleppinger bipolar forceps and a monopolar electrode were applied to stop bleeding but in vain. Diluted vasopressin (0.5 U/mL) was then injected around the mass and it stopped the bleeding. The internal bleeding was estimated at 1700 mL. The woman was discharged 2 days later and was followed up at the outpatient clinic with ultrasound and physical examination for the possibility of recurrent bleeding. Serial β-hCG showed decreasing levels and was undetectable 15 days later. Traditionally, interstitial pregnancies require cornual resection or even hysterectomy. However, cornual resection might compromise future fertility and increase the risk of uterine rupture during a subsequent pregnancy. With increasing experience and success using methotrexate to treat ectopic pregnancy, conservative medical treatment is gaining more popularity. Originally, methotrexate treatment was only limited to ectopic pregnancies of 3.5 cm or less in diameter and without cardiac activity (2). As more experience accumulates, these became only relative contraindications. Even interstitial pregnancy with an initial β-hCG level up to 102 000 mIU/mL has been reported being successfully treated medically (3). This case extends the use of methotrexate even further, demonstrating that the rupture of an interstitial pregnancy may not be an absolute contraindication of methotrexate. Methotrexate can be given either systemically or locally, or a combination of both. The overall success rate of methotrexate therapy was 83%, with local injection slightly more effective than systemic injection (91% and 79%, respectively) (4). Local injection has another advantage of fewer side effects. There are several regimens of methotrexate treatment, but there is no evidence that one is superior to the other. The most commonly used dosage is 1 mg/kg and 50 mg/m2, either a single dose or multiple doses. This case demonstrated that a ruptured ectopic pregnancy is not an absolute contraindication to medical treatment. However, it is not our intention that all ruptured interstitial pregnancy or hemodynamically unstable patients can be treated with methotrexate. Nonetheless, if the bleeding is not very active, the use of methotrexate injection combined with electrocauterization and vasopressin to stop bleeding from the gestational site can be effective for treating a ruptured ectopic pregnancy.