Twin transfusion syndrome is a serious complication of monozygotic twin pregnancy. Diagnostic ultrasound now allows early diagnosis of this condition, but therapy has remained more elusive. In this article we present a case of severe twin transfusion syndrome diagnosed early in the second trimester. At 25 weeks' gestation, severe hydramnios, premature labor, and growth retardation of the donor twin suggested that selective feticide be contemplated to allow continuation of the pregnancy for the remaining twin. This was accomplished successfully by an in utero approach with subsequent follow-up and delivery of a healthy female infant at 37 weeks' gestation. Discussion of diagnosis, management, follow-up, and pathologic features is provided.