The main objectives of this study were to investigate the association between childhood violence and psychological distress and post-traumatic stress symptoms (PTS) among Sami and non-Sami adults, and to explore a possible mediating effect of childhood violence on any ethnic differences in mental health. This study is part of a larger questionnaire survey on health and living conditions in Mid- and Northern Norway (SAMINOR 2) which included 2116 Sami and 8674 non-Sami participants. A positive association between childhood violence and psychological distress and PTS in adulthood was found regardless of ethnicity. For women, childhood violence may have mediated some of the ethnic differences in psychological distress (53.2%) and PTS (31.4%). A similar pattern was found for men as to psychological distress (45.5%) and PTS (55.5%). The prevalence of psychological distress was significantly higher in the Sami than in the non-Sami group: 15.8% vs. 13.0% for women, and 11.4% vs. 8.0% for men. Likewise, PTS showed a higher prevalence in the Sami group, both for women (16.2% vs. 12.4%) and for men (12.2% vs. 9.1). Conclusion: A positive association between childhood violence and adult mental distress was found for both Sami and Norwegian adults. More mental problems were found among the Sami. Childhood violence may have mediated some of the ethnic differences.