INTRODUCTION: The Self-Efficacy for Managing Chronic Disease 6-item Scale is a widely used questionnaire instrument for measuring self-efficacy. Since self-efficacy has increasingly been recognised as an essential prerequisite for effective self-management of chronic diseases, valid and reliable measures are needed to do evaluations in research and clinical practice. This study aimed to translate and perform linguistic validation of the questionnaire for use in a Danish population and context. METHODS: The translation and validation process, which followed the International Society for Pharmacoeconomics and Outcome Research guidelines, included professional translation and back translation, facilitated by clinical experts. Furthermore, we conducted cognitive debriefing interviews with patients diagnosed with chronic diseases. RESULTS: The questionnaire was translated into Danish and linguistically validated, each step producing changes leading to a more conceptually and culturally equivalent Danish version. The back translation was compared with the original English version which led to the identification of discrepancies requiring discussion before the next back translation. Ten participants were recruited for the cognitive debriefing interviews and contributed to minor changes. CONCLUSION: The Danish version of the Self-Efficacy for Managing Chronic Disease 6-item Scale is ready for use among Danish-speaking patients with chronic diseases. FUNDING: This work was supported by the Models of Cancer Care Research Program with grants from the Novo Nordisk Foundation (NNF16OC0022338) and Minister Erna Hamilton's Grant for Science and Art, (06-2019). The funding source did not contribute to the study. TRIAL REGISTRATION: not relevant.