The aim of this study was to investigate the effect of oropharyngeal aspiration on ventilator-associated pneumonia (VAP) incidence just prior to changing patient position. This randomized controlled experimental study was conducted between July 2015 and April 2019 in anesthesiology and reanimation of intensive care unit (ICU). The patients of experimental group underwent oropharyngeal aspiration under surgical aseptic conditions before each position change. Patients of the control group received oropharyngeal aspiration only as needed. The mean age of the patients was 62.87 +/- 17.33 years. The mean and median duration of stay in the ICU were 27.28 +/- 30.69 and 18.00 days respectively. The mean and median of duration of the mechanical ventilation support were 26.72 +/- 30.65 and 18.00 (min 4; max 168) days respectively. Thirty percent of the patients were VAP. The mean duration of VAP development was 7.50 +/- 5.07 days. The rate of VAP development was 11.23/1000 mechanical ventilator days. Only 8.3% of the experimental group patients developed VAP; 91.7% of the control group patients developed VAP. The VAP rate in the control group was 16.82/1000 mechanical ventilator days and the VAP rate in the experimental group was 2.41/1000 mechanical ventilator days. Most VAP agents were multidrug resistant. Distribution of isolated microorganisms was as Acinetobacter baumannii, Pseudomonas aeruginosa, Corynebacterium striatum, Staphylococcus aureus, Providencia stuartii, Serratia marcescens, Stenotrophomonas maltophilia, and Aspergillus flavus. In our study, it was concluded that oropharyngeal aspiration performed prior to patient position change prevented the development of VAP.