In this study, the emmission of the Bacterial bioaerosols in the different respiratory system in a neonatal intensive care unit (ICU). In this study, a six-stage Andersen impactor was used for the sampling of bioaerosols with a flow rate of 28.3 L / min. The concentrations obtained from bacterial bioaerosols ranged between 67 and 423 CFU / m3, with an average value of 110.13 CFU / m3, which can represent a possible threat to the health of the workers and neonates in the ICU. The results indicated than Staphylococcus saprophyticus and Staphylococcus epidermidis predominated, especially in the fifth and sixth stages, which means second bronchi and alveoli. While Staphylococcus was the most prevalent genus, Alloiococcus otitidis, Bacillus subtiles, Bacillus thuringiensis, Kocuria rosea and Pseudomonas pseudoalcaligene occurred in the alveoli.