Fetomaternal bleeding is the major cause for rhesus immunization in pregnancy. This study evaluates the amount of fetomaternal bleeding in 345 pregnancies before 28th week of gestation. Fetomaternal bleeding was of clinical relevance (HbF greater than 0.015%) in 2.2% of all uncomplicated pregnancies. In case of abortion or vaginal bleeding in early pregnancy we observed a statistical significant increase of transplacental hemorrhage. The need for anti-D-prophylaxis in this patients is obvious.