The purpose of this review is to summarize recently published studies on noninvasive diagnosis of fetal anemia in order to give recommendations for the use of these new tools.Red cell alloimmunization remains one of the most common causes of fetal anemia. Amniocentesis and cordocentesis have been used for many years to diagnose fetal anemia due to red cell aloimmunization. These techniques, however, are invasive and many complications are associated with their use. Noninvasive diagnosis of fetal anemia has been performed with Doppler ultrasonography. Based on robust data, several authors recommend the use of middle cerebral artery peak systolic velocity in the management of fetuses at risk for anemia because of red cell alloimmunization. This Doppler parameter can also diagnose fetal anemia due to other conditions.Middle cerebral artery peak systolic velocity appears to be the best test for the noninvasive diagnosis of fetal anemia. It is important to emphasize that training of sonographers and sonologists is the 'conditio sine qua non' for the correct sampling of the middle cerebral artery.