In 95 healthy delivered women the placenta (externally and internally) and the amniotic sac were examined for mycoplasma population. Mycoplasmas could not be identified in any of the cases under investigation. In healthy pregnant women, mycoplasmas are not identifiable as "harmless commensals" either in the amniotic sac or in the placenta. In cases where mycoplasmas are found, they may act as pathogens.