Prevalence of air borne Nosocomial infection is a major attribute to morbidity and mortality in immunocompromised patients. Two methods are commonly used for measurement of bacterial density in hospital environment particularly Operation theater. Air samples from conventionally ventilated operating rooms and intensive care units were taken simultaneously by the sedimentation method (settle plate) and with the HiAir petri air sampler. Bacterial density was calculated in form of colony forming unit (cfu). The isolated bacteria were identified by conventional methods. The investigations showed that the number of colony forming units per cubic metre obtained with the sedimentation method was, on an average, higher than those found with the HiAir petri air sampler from the same area. The most common isolate from settle plate method was Bacillus subtilis (54.91%) followed by Pseudomonas aeruginosa (38.09 %), Co-agulase negative staphylococcus (30.12%), Klebsiella pneumoniae (25.85%), Acinetobacter baumanii (23.12 %), Escherichia coli (10.22 %), Staphylococcus aureus (8.32%) and Proteus mirabilis (2.72%). Settle plate method was found to be more informative than the air sampling system for bacteriological analysis of air in present study.