The current study aimed to evaluate six types of commercial disinfectants available in the local markets and the most commonly used at the farm level within poultry flocks in Egypt in terms of their ability to stop common microbial species (total aerobes, yeast, and mold) and their resistance through different methods of application (Low rate Spray, High rate Spray, Cold Fogging). It is utmost significant to remember that for the field trials ,all surface wastes and loose animate matter had been removed before disinfectant application. Method and rate of application are very important to obtain efficient disinfection process as well as complete destroying of pathogens or even minimizing the level to ensure the prevention of the infection. A study was carried out at faculty of veterinary medicine Cairo University, the disinfectants Formalin, QACs, Phenol, Virkon-S, Halamid, and Micro-Sept M were chosen.  The results showed that: A) At low application rates, disinfectant treatments had no noticeable effect on total aerobic bacterial populations excluding Formalin and Virkon-S, where the decrease in log 10 was 2 and 1.7, respectively compared with the  control group ). B) High application rates of selected disinfectants impacted and affect significantly the examined microorganisms. C) Cold fogging resulted in the greatest effect among other two above mentioned experiments on aerobic bacteria, yeast, and mold populations. Concerning, mold: Fogging resulted in a significant effect of selected disinfectants.