OBJECTIVES A wide range of instruments are used to measure outcomes in clinical studies of chronic pain. However, the suitability of study outcomes for economic evaluations in chronic pain is limited by variability in the instruments used and the failure of those that are in common use to adequately capture  the dimensions of a patient’s experience of pain, including function, quality of life and tolerability. The current study aims to identify the pain instruments and study endpoints most commonly used in the clinical trial setting. METHODS A structured, comprehensive literature review of ongoing registered trials (trial registries) and published clinical studies (PubMed) in the areas of chronic pain (cancer, non-cancer and neuropathic), pain in elderly patients, and breakthrough pain was conducted. Inclusion criteria were: interventional study, pain population of interest and pain measured within primary endpoint.  Data were extracted from identified publications focusing on primary and secondary endpoints reported, and primary pain instrument used. RESULTS Of 1,256 citations retrieved, 132 were included as they reported large clinical studies in pain populations. The majority of primary endpoints were pure pain measures (112), most commonly: numerical rating scale (NRS) (44), visual analogue scale (VAS) (34), and brief pain inventory (BPI) (18). Other outcome domains were typically limited to secondary endpoints and were not consistently applied across the studies. These include measures of function (47), quality of life (36), safety/tolerability (33), emotional wellbeing (26) and sleep (20). CONCLUSIONS The majority of studies still use simple pain measures as their primary outcomes. Useful economic outcomes such as quality of life and function are relegated to secondary endpoints and are inconsistently used. Types of pain instruments currently used in registered, ongoing trials will also be reported. Further research is needed to consider which existing endpoint designs constitute best practise and if new designs are required.