Background and aims: The language in assessing intensity or quality of pain has been studied but the results have been inconsistent. The physicians' language skills might affect the estimation of the severity of pain possibly leading to insufficient use of analgesics. Several interfering cultural factors have complicated studies aimed at exploring the language used to detect the quality of pain. We aimed to compare native and non-native language related qualitative aspects of pain chosen by Swedish speaking patients with diabetes. Methods: In the study participated 10 Finnish and 51 Swedish speaking patients with diabetes. The Pain Detect-questionnaire was used for clarifying the patients' pain and the mechanism of their pain (neuropathic or not) and for assessing the intensity and quality of pain. In addition, the patients completed the short-form McGill Pain Questionnaire (sfMPQ) in Finnish (test I). After 30 min the subjects completed the sfMPQ a second time in their native language (test H). The Swedish speakers estimated their second language, Finnish, proficiency on a 5-graded scale. Results: There were significantly more discrepancies between sfMPQ test I and test II among the Swedish speaking respondents who reported poor (hardly none) Finnish language proficiency compared with those with good Finnish proficiency. Discrepancies occurred especially between the affective qualities of pain. Conclusions: Poor second language proficiency exposes Swedish speakers to pain communication difficulties related to the affective aspects of pain. Consequently, discordant language communication could cause underestimation of the severity of pain and pain undertreatment.Peer reviewe