Purpose: This study aimed to evaluate the impact of oral care and use of chlorhexidine gluconate on the prevention of ventilator-associated pneumonia (VAP) in patients admitted to an intensive care unit (ICU). Materials and Methods: An evaluation was performed on 229 patients admitted to ICU in 2012 (before implementation of oral care protocol) and 329 in 2013 (after the protocol). Oral care was based on the removal of secretions from the oral cavity with 0.12% chlorhexidine solution for brushing and sterile gauze for cleaning before a new aspiration. The cases of VAP were evaluated by observing respiratory signs, radiological changes, and culture and laboratory results. The following data were also analysed: gender, length hospital of stay, mechanical ventilation, use of antibiotics and aetiological agent of infection. Results: There was a tendency towards lower risk of development of VAP after application of oral care protocol (odds ratio = 0.64–95% CI: 0.39–1.04). There was also a reduction in the incidence of early pneumonia (up to 72 h of hospitalisation). With regard to the aetiological agent of infections, although Gram-negative bacteria predominated in the two periods studied, there was a decrease in the cases of Staphylococcus aureus infection. Conclusion: Oral care protocol has statistically significantly reduced the risk of developing early VAP in ICU patients, thus demonstrating the importance of multidisciplinary teamwork for hospitalised patients. Keywords: chlorhexidine, mechanical ventilation, oral care, pneumonia