BACKGROUND: The assessment of pain intensity is mandatory in many medical disciplines. However, several pitfalls are associated with this task, as, for example, the selection of an instrument which is suitable for different groups of patients; the reliable and valid interpretation of the results, etc. Thus, the aim of the present review is to summarise the recent literature on this topic and to provide a selection of suitable instruments to assess pain intensity in different groups of patients. METHODS: The recent literature was screened and summarised. RESULTS: Assessment of pain has to be performed in consideration of the target population (e. g., age, health condition, cognitive function). CONCLUSIONS: The selection of appropriate pain measurement scales is mandatory for achieving valid results.