SUMMARYIntroduction: Research shows that intensive care patients experience pain both at rest and during procedures. Critically ill patients frequently have impaired ability to communicate pain and discomfort, making pain assessment and pain management challenging. Systematic pain assessment with valid tools is essential for good pain management. The Critical-Care Pain Observation Tool (CPOT) is a pain assessment tool with four domains.Objective: To translate The Critical-Care Pain Observation Tool (CPOT) and to examine the tool's validity and reliability.Method: The study has a descriptive quantitative design. The CPOT was first translated into Norwegian using an internationally recommended translation process. Six intensive care nurses were given a one-hour training session in the use of the CPOT, and an instruction video was used to achieve a common understanding of the CPOT scoring system. Independently, two intensive care nurses (in pairs) assessed and scored the patient's pain expression, using the CPOT, before and during a turning procedure. A total of 182 (91 pairwise) CPOT assessments were performed of 18 intensive care patients on mechanical ventilation. The Norwegian version of the CPOT was examined for discriminant validity by comparing the nurses' scores before and during the turning procedure. Research shows that intensive care patients frequently suffer from undertreatment of pain (1)(2)(3)(4)(5). Undertreatment of pain can have serious physical and psychological consequences (6-8). The golden standard for pain assessment is the patient's own description of pain (9, 10). However, the intensive care patient's impaired ability to communicate entails that the patient may experience pain without being able to express it in a way that health care personnel comprehend (4, 7, 11). Patients' inability to self-report pain hinders effective pain management.Systematic pain assessment with valid tools has proven essential to good pain treatment and may be used as a quality indicator of clinical practice (12, 13). There are several tools for assessing pain in adult intensive care patients, but according to international clinical guidelines (14), The Behavior Pain Scale (BPS) (15) and The Critical-Care Pain Observational Tool (CPOT) (16,17) have the highest validity and reliability. Rijkenberg et al. compared the CPOT and the BPS and concluded with a preference for the CPOT, due to better discriminant validity, meaning the tool measures pain better when the intensive care patient is assumed to have pain (19).In the international clinical guidelines, Barr et al. refer to the testing of the two tools' psychometric characteristics (measurement characteristics, user friendliness, the tool's validity and reliability, etc.). The CPOT appeared to be somewhat better, but both the CPOT and the BPS are equally recommended (14). The guidelines recommend that the CPOT and the BPS be translated and validated into more languages (14). The BPS is translated into Norwegian and tested for reliability by Olsen and Rustøen (18). ...