The authors report on a twin pregnancy with one phenotypically normal twin and one with Prune-Belly-syndrome. Since a severe urethral obstruction-malformation complex was apparent, a premature vaginal delivery was aimed for. A pathologic CTG of the healthy twin, with silent and sinusoidal graph pattern, rendered a primary cesarean section necessary in the 36th + 0 week of pregnancy. The cause was established as a fetofetal transfusion syndrome with severe anemia of the phenotypically normal newborn. Following appropriate blood transfusion the subsequent development of this child was free of complications. The child with Prune-Belly-syndrome died on the second day of life.