Klippel-Trenaunay syndrome (KTS) is a rare congenital disease, and extensive cutaneous hemangiomas and abnormal venous vessels are characteristic. In our case, to manage her pregnancy with KTS, whole-body MRA was performed before delivery. A 29-year-old woman was referred at 28 weeks because of prominent vulvovaginal varicosities due to KTS. At 35 weeks, hypertrophy and multiple venous varicosities of her leg as well as massive vulvovaginal varicosities became prominent with a normal coagulation profile. Systematic MRAs revealed hemangiomas and varicosities in the right leg, the lower abdomen, and the pubic region, while no obvious AVM was detected around the bronchial tube and spine. We decided to deliver her baby by cesarean section at 37 weeks under general anesthesia, and a healthy baby was delivered. No blood transfusion was required. Prophylaxis against thrombosis was performed after the operation. She was discharged with her baby. Her vulvovaginal varicosities shrunk considerably one month later.