A large hepatic cyst was diagnosed in a fetus at 29 weeks of gestation by puncture and aspiration performed under ultrasonographic guidance. This procedure was repeated five times at about 2-week intervals, with a total of 1,446 ml of cystic fluid aspirated. A healthy female infant was delivered vaginally at 40 weeks of gestation. Her Apgar score was 9 at 1 min, and she weighed 2,790 g. On the 14th postnatal day, the hepatic cyst was punctured percutaneously under ultrasonographic guidance, and 119 ml of yellow fluid was aspirated. The cyst was subsequently not visible on computed tomography at 9 months. Surgery was not indicated in this infant, and the cyst was also not detected at the age of 21 month. Thus, treatment in utero appeared to have obviated the need for surgery.