Surgical site infection risk due to airborne bacteria is a key area of consideration in developing operating theatre ventilation design and monitoring procedures. This paper reviews the recent extensive research into operating theatre ventilation development in relation to the design concepts in operating theatre layout, pressurization and ventilation, particularly the evolvement of ultra-clean ventilation. The findings that led to the current technical standards and the developments of microbial measurements and numerical techniques are discussed. Since the late 1980s, computational fluid dynamics has been a fast developing tool used in the prediction of room air distribution and contaminant dispersion. The basic principles and current practice applying to operating theatre ventilation studies are introduced.