Studies have shown that 60 to 80% of the patients in nursing homes experience pain and that 50 to 70% are cognitively impaired. A major problem in pain assessment in these patients is lack of communication caused by the cognitive impairment. Thus a substantial number of patients are unable to report pain and consequently health care providers fail to offer them an appropriate treatment. Although self assessment of pain is seen as the golden standard, several recent reports have argued for the value of proxy raters. The French DOLOPLUS group has developed and validated a pain assessment tool based on behaviour rating in the cognitively impaired patients. Internationally, well accepted and validated tools should be the standard for all type of pain assessment. Few, if any pain assessment tools fit these criteria today for the given population. Therefore we have decided in collaboration with the French DOLOPLUS group to perform a translation and validation of the instrument in Norwegian. As a first phase in the validation procedure the pain assessment tool was tested at four different nursing homes. The nurses at the wards, in collaboration with a research assistant, used the Doloplus on 59 cognitively impaired nursing home patients. The results were compared against an experienced clinician's pain ratings. Regression analysis showed that the Doloplus score could account for 62% of the true score, using the expert clinicians as "the golden standard". The analysis of the unstandardised residuals showed that two thirds of the Doloplus scores felled within 1 standard deviation from the expert score. A nonparametric correlation analysis showed a correlation between these scores of 0.69. A debriefing questionnaire was delivered by the users of the Doloplus. All users concluded that Doloplus was helpful, easy to administer and that important new information about pain was collected. We conclude that the Doloplus seems to have satisfactory validity in this pilot study, and it is user friendly for pain assessment in the cognitively impaired patients. Further validation studies are necessary, ideally in an international context.