Ventilator-associated pneumonia (VAP) is a nosocomial infection that can develop in patients receiving mechanical ventilator (MV) support. VAP has a high mortality rate and cost due to prolonged hospitalisation. Some procedures have s hown that VAP can be prevented. However, the incidence of VAP is still high in Turkey. In this study, we aim to investigate how increased compliance with VAP prevention bundle training for health personnel affects the incidence of VAP, the onset day of VAP , the duration of mechanical ventilation, and mortality rates. This prospective case control study was started after obtaining permission from the Van Yuzuncu Yil University (VYYU) Medicine School Ethics Committee. It was conducted between November 2017 and June 2018 at the Anesthesiology and Reanimation Intensive Care Unit (ICU) of the Dursun Odabaş Medical Center, VYYU Medicine School. In this study, the study group (VAP prevention bundle group after healthcare staff training) included 68 patients who rec eived MV support. The control group consisted of 100 patients who received the VAP prevention bundle between January 2016 and June 2017 in the anaesthesia ICU. The Centers for Disease Control and Prevention (CDC) criteria were used for the diagnosis of VAP. In both groups, compliance with the Prevention Bundle, the incidence of VAP, the onset day of VAP, the duration of mechanical ventilation, th e day of tracheostomy operation and mortality rates were recorded. Patient groups were compared statistically. The demographic data, diagnosis and cultured microorganisms in VAP patients were similar and there was no statistically significant difference. The effect of four parameters [Endotracheal tube with subglottic secretion drainage (SSD -ETT), 0.12% chlorhexidine oral care, peptic ulcer prophylaxis and deep venous thrombosis (DVT) prophylaxis] that were included in the VAP Prevention bundle could not be evaluated separately because of the mean fit. The mean fit in holding the bed head position at an angle of 30°–45° was 100% in the VAP Prevention bundle group, while in the control group the average was 90.67% (85 -100%). The relationship between this and the development of VAP was statistically significant (p=0.036). ETT cuff pressure of 20 –25 cm H2O was maintained at 97.96% in the VAP Prevention Bundle group and at 93.13% in the control group . The difference between the groups according to the accordance to the ETT cuff pressure was statistically significant (p=0.01). In our study, VAP was detected in 12 patients (17.6%) in the study group and 9 patients (9%) in the control group. There was no statistically significant difference between the groups in terms of VAP or the duration of mechanical ventilation support (30.29 ± 24.5/26.11±15.47). No early development of was seen in either group (first four days after MV support). It was determined that all VAP attacks developed after the fifth day of MV support. For 1000 ventilator days, onset of VAP was 13.1 days in the VAP prevention bundle group and 4.29 days in the control group, which was not statistically significant (p = 0.96 ). Although the mean number of days of VAP-developing groups in relation to MV was 44.83 ± 30.845/82.22 ± 55.432, it was not statistically significant. In the VAP prevention bundle group, the mean day of application of tracheostomy was 7.09 ± 7.12 while it was 16.67 ± 9.11 in the control group; this difference between the groups was statistically significant. Although the mortality rate was increased in patients with VAP, it was not statistically significant. However, mortality rates were significantly lo wer in patients without VAP as compared to the control group (p