The aerobic culture from nasal cavity of 49 newborn babies who were normally delivered and from vagina of 20 pregnant women during labor was done. At the same time, aerobic culture of the air in delivery room eight times and nursery room five times was performed. And the results were as follows : In conclusion, the aerobic culture from the nasal cavity of newborn babies was positive in 20 babies(40.8%) and we could suspect that nasal cavity of newborn babies was primarily sterile but might be contaminated during the labor from birth canal or in the delivery and nursery room.