relieving distressing symptoms and managing the side effects of analgesics are essential in order to improve quality of life and functional capacity in chronic non-cancer pain patients. A quick, reliable and valid tool for assessing symptoms and side effects is needed in order to optimize treatment. We aimed to investigate the symptoms reported by chronic non-cancer pain patients after open-ended questioning vs. a systematic assessment using a list of symptoms, and to assess whether the patients could distinguish between the symptoms and the side effects induced by analgesics.