Background: Patients on a ventilator often experience pain. Pain experienced by patients can be minimized by proper assessment of pain. The appropriate wound assessment instrument for ventilated patients is the Critical Care Pain Observational Tool (CPOT). CPOT is one of the coding instruments for adult patients that is mounted on a ventilator and is used for patients who cannot report complaints verbally. The purpose of this study was to describe the assessment of pain using CPOT in ventilator mounted patients. Materials & Methods: The design used a literature review with 10 article participants using the Pubmed, Proquest, Google Scholar search system. Journal analysis Literature Review on 10 journals was carried out using PICO analysis. Results: The results obtained CPOT instrument has a high enough value. CPOT measurement results have a good level of conformity from BPS measurement results. CPOT is a measuring tool that is more relevant, valid, and responsive than the Wong-Baker scale to assess comfort in ventilated patients. Conclusion: CPOT is easier to use because it has clear operational resolutions on each item of observation.