Background: Oral care is vital nursing action for intubated patients that aims to reduce the mortality and morbidity among intensive care unit patients by preventing Ventilator-associated pneumonia.Aims of the study: The study aimed to assess the nursing staff's knowledge toward oral care of intubated patients before and after the implementing the educational program.Methodology: A pre-experimental (one-group pre\post-test) design is used to conduct this study which was in the period 22 \ December \ 2020 to 2 \ May \ 2021. The non-probability (purposive) sampling is used to select the study sample that composed of (27) nursing staff working in the ICU in Al-Diwaniya Teaching Hospital. To achieve the objectives of the study, the researcher constructed the study instruments consisting of the educational program and the knowledge questionnaire. The questionnaire consisted of two parts: the first part related to the demographic characteristics of the nursing staff participating in the study, and the second part which consisted of (25) multiple-choice questions distributed on (4) domains to assess the knowledge of the nursing staff towards the oral care of the intubated patients. To analyze the results, descriptive statistics (frequencies, percentage, arithmetic mean, standard deviation) and inferential statistics (ANOVA, t-test) were used.Results: The study showed that there are significant differences between nurses' knowledge scores in the post-test when compared to their scores in the pre-test (M=.082 in the pre-test, while in the post-test, M=.093). The study also showed there is a significant relationship only between nursing staffs' knowledge and their level of education.Conclusion: The study concluded that the educational program has a positive effect on the nursing staffs' knowledge regarding oral care for intubated patients in Al-Diwaniyah Teaching Hospital.Recommendations: The study recommended the necessity of using the oral care protocol in the intensive care units and urged the nursing staff to participate in educational and training courses on oral care in intensive care units.