Translation of questionnaires and issues of equivalence¶ The validity of studies using translated instruments may be questioned when there is a lack of attention to and/or minimal explanation of the procedures used for determining the equivalence between the primary and secondary language tool. Ensuring equivalence of a translated Chinese version of the Menstrual Distress Questionnaire is an important prerequisite for identifying culturally specific expressions of concepts under investigation and for cross-cultural comparisons. This paper examines the principles and procedures for determining equivalence of translated tools and their application to the development of an equivalent Chinese version of the Menstrual Distress Questionnaire. Translation and back-translation were used to develop a Chinese version of the Menstrual Distress Questionnaire. Bilingual university students completed both versions of the Menstrual Distress Questionnaire. Most of the Menstrual Distress Questionnaire items had an acceptable Kappa openface> 0·4. Intraclass correlation coefficients indicated moderate to high levels of equivalence for total scores and all scales. Improvement in the translation of some items is needed to further enhance the equivalence of the Chinese version of the Menstrual Distress Questionnaire.