The bioaerosol concentrations in a hospital ward were investigated with varying recirculation rate, ventilation rate, and filtration efficiency. The mathematical model for the dispersion of bioaerosols in a hospital ward having 8 rooms with total 26 beds was generated using adapted mass balance equations. When the hospital room was occupied only by patients and guardians, the bioaerosol concentration did not exceed the Korean regulation limit, 800 CFU/㎥, for multipurpose buildings. The bioaerosol concentration in a single room was about 50CFU/㎥ lower than ones in multi-bed room. When a HEPA filter was installed in an air handling unit, the bioaerosol concentration decreased by about 50% compared to the bioaerosol concentration without filter.