After giving 5 g Ampicillin intravenously to a total of 33 women (gravidae during the VIII. month pregnancy, women in labor and health controll persons) the serum levels of the mothers were analysed according to the pharmacokinetic parameter half-life of elimination.--Our results show that only the delivery cause significant differences of the kinetic of ampicillin.--Our results are discussed with the data given by literature.