Background: Nowadays, the individual differences are emphasized in personalized medicine. Traditional Chinese Medicine (TCM) which prescribes tailored treatment based on each patient’s different body constitution may provide new strategy to break the bottleneck of modern medicine (MM). Therefore, to integrate TCM into MM, an objective, reliable and rigorous diagnostic tool is necessary for the assessment of TCM constitution of each individual. This study aimed to develop a provisional version of the Yin-Xu Constitution Questionnaire (BCQ–), because evaluating the level of individual’s Yin deficiency (Yin-Xu) by his manifestations is frequently involved in TCM clinical trials. Methods: The provisional version of BCQ– was developed using a step-by-step approach: 1) to form the research team and select a panel of 26 experts who had both MM and TCM educational background and professional training for Delphi method; 2) to generate questionnaire items from literature review and Delphi process, refine these items to be colloquially acceptable, and evaluate their face and content validities by Delphi process again; 3) to evaluate the difficulty of answering these questions by a pilot study with 81 participants whose age ranged from 20 to 60 years. Results: After 2 rounds of Delphi process, 22 colloquially appropriate questions were established and answered without difficulty by the 81 participants. Conclusions: This provisional version of BCQ– appeared to have considerable face and content validities and may be the basis to develop an advanced Yin-Xu questionnaire. The reliability and validity of BCQ– were further tested in the second part of the study.
