OBJECTIVES: This study aimed to examine the psychometric properties of a Swedish version of the Medical Outcomes Study Social Support Survey (MOS-SSS). METHODS: Standard forward-backward translation was used. A cross-sectional survey was conducted among treatment seeking individuals with chronic pain included in a clinical cohort. Internal consistency was measured with Cronbach's α, test-retest reliability was examined with intraclass correlation, confirmatory factor analyses was used for examining factor structure, and correlations between the MOS-SSS and selected health validity measures were used for testing concurrent validity hypotheses. RESULTS: 182 participants were included in the study. Internal consistency measured with Cronbach's alpha was acceptable for all subscales and for the total support index of the MOS-SSS. Test-retest reliability was moderate - good for the different subscales, and was good for the overall support index. The original four factor model of the MOS-SSS was confirmed, and the concurrent validity hypotheses were also confirmed; however, the associations were weaker than expected. CONCLUSIONS: The Swedish version of the MOS-SSS was found psychometrically sound and offers a systematic assessment of social support in specialized pain care.