Twin-twin transfusion develops in 10-20% of monochorionic twin pregnancies. As far as we know the underlying disturbance is an unbalanced anastomosis between the two fetuses on the placental surface. Without treatment mortality is as high as 80% if diagnosed before viability. One of this article's authors spent two months in Hamburg at the 'Allgemeine Krankenhaus', Barmbeck in Germany and describes the technique used there to coagulate these anastomoses via fetoscope. The outcome seems very promising with overall survival of 80% using this method. In the article pathogenesis and alternative treatments are also discussed.