Context: Studies show that despite the role of mouth care in preventing ventilator-associated pneumonia, there is no high quality evidences for it. This study reviewed the literature related to mouth care in patients receiving mechanical ventilation. Evidence Acquisition: PubMed, Ovide, Elsevier, ProQuest, IranMedex, SID, and Magiran databases were searched using key terms such as oral care, mouth care, critical care, and intensive care. Fifty-seven full-text articles in total were retrieved and included in the study. Results: Totally, 15 review articles and 42 research articles were reviewed. Only 13 articles introduced or evaluated the validity of instruments or caring guidelines in the area of mouth care. Only one study discussed about designing and validating the psychometric properties of a mouth assessment scale. Most of the articles emphasized on brushing the teeth as the best method for mouth care, but there was no consensus on the frequency of washing and the best washing solution. Conclusions: Despite the importance of mouth care, few original studies are conducted in this area and there is no approved clinical guideline for this procedure. Published by Kowsar Corp, 2012. cc 3.0.