Monoamniotic twins have a mortality rate of up to 50%, mainly due to umbilical cord accidents, e.g. true knots. Because of the rarity of monoamniotic twin gestation, few data are presently available on the optimal management of these gestations. Some authors recommend delivery at 32 weeks of gestation, while others state that the risk of cord accidents declines with advancing gestational age, thus questioning the usefulness of routine delivery at 32 weeks. It is possible nowadays to obtain an impression of the fetal blood supply by Doppler sonography. In our case, Doppler sonographic evaluation showed a notch in the umbilical artery in the twin, who later developed a pathological CTG requiring delivery at 28 weeks of gestation. Both fetuses are liveborn and developed normally. Our case shows that a notch in the umbilical artery could be an indication of umbilical cord compression and that attention should be paid to it in monoamniotic twin gestation.