The Numeric Rating Scale (NRS) is suitable in postoperative settings, yet, the implementation has shown varying results. This has raised issues about the pain scales contribution to the identifying and understanding of pain. The aim of this thesis was to describe the clinical utility of patients’ self-rated postoperative pain after major surgery from a healthcare professional perspective. The aim of study I and II was to describe healthcare professionals’ perceptions of the use of pain scales, and to through considering critical incidents describe care experiences and actions taken by healthcare professionals’ when assessing pain. Participants in study I (N=25) and II (N=24) were enrolled- registered nurses and physicians with clinical experiences of pain scales. The aims of study III and IV were to determine the clinical applicability of NRS mode- and maximum- measures, and the NRS mode- and median measures at rest and during activity based on patients self-rated pain. The aim in study IV was additionally to determine the number of NRS ratings needed for the calculation of these measures. The number of surgical and orthopedic patients who completed study III were: n=157 and study IV: n=479. Study I and II confirmed earlier findings of patients’ self-reported pain scores as a facilitator in the understanding of their postoperative pain. Organizational routines, documentation devices, clinical competence, continuity in care, collaborative actions, time, and individual routines were healthcare related factors affecting the use of pain scales (I, II). Patient-related facilitating factors were patients’ ability and willingness to communicate pain, while disability and unwillingness to communicate or inconsistency in verbal communication with observed behaviors were barriers (II). Time and multidimensional communication approaches could bridge these barriers (I, II). Study III and IV showed acceptable reliability for the mode, median and maximum measures. Rank correlations for individual median scores, based on four ratings, versus patients’ retrospective self-rated average pain, were moderate and strengthened with increased numbers of ratings. The Svensson method showed an individual variation within the expected outcome and a significant systematic group change towards a higher level of reported retrospective pain. The calculated pain measures, particularly concerning pain at rest, generally were lower than patients’ recall of pain. The findings described beneficial effects of patient self-reported pain, however present healthcare did not fully support the utilization of pain scales. Because of the simple measurement characteristics, the use of daily NRS average pain measures, patients’ pain can be followed until resolved. The measures could additionally become important patient reported outcome measures and thus constitute new motivators to increase the utilization of pain scales.