A study of 350 newborn girls revealed vaginal (uterine) bleeding in 25,4%, mostly demonstrable only by chemical micro-methods, but also macroscopically visible in 3,3%. This kind of bleeding appears always in the first week, with its highest frequency on the 5th day of life and must be regarded as a physiologic event. Analogous histologic and cytologic controls confirmed these observations, pointing toward the fact that, as a rule, no menstrual withdrawal bleeding, but degenerative, regressional changes upon the endometrium occur. Due to the rapid withdrawal of maternal hormones, nutritive disorders may lead also to diapedesis bleeding. But if any genital bleeding lasts longer than one week or appears for the first time after that period, further diagnostic procedures are essential as a possible pathologic condition may be assumed.