The objective of the present study was to translate and validate the Canadian Readiness for Return To Work instrument (RRTW-CA) into a Danish version (RRTWDK) by testing its test–retest and internal consistency reliability and its structural and construct validity. Cross-cultural adaptation of the six-staged RRTW-CA instrument was performed in a standardised, systematic five-step-procedure; forward translation, panel synthesis of the translation, back translation, consolidation and revision by researchers, and finally pre-testing. This RRTW-DK beta-version was tested for its psychometric properties by intra-class correlation coefficient and standard error of measurement (n = 114), Cronbach’s alpha (n = 471), confirmatory factor analyses (n = 373), and Spearman’s rank correlation coefficient (n = 436) in sickness beneficiaries from a municipal employment agency and hospital wards. The original RRTW-CA stage structure could not be confirmed in the RRTWDK. The psychometric properties were thus inconclusive. The RRTW-DK cannot be recommended for use in the current version as the RRTW construct is questionable. The RRTW construct needs further exploration, preferably in a population that is homogeneous with regard to cause of sickness, disability duration and age.