Objective To investigate the prevalence and distribution of Yin and Yang deficiency syndrome on different nationalities in different parts of Xinjiang in order to offer epidemiology evidence for the research on the cause of dryness syndrome in northwest China.Methods The questionnaire was designed according to the Chinese medicine theories and the sampling questionnaire investigation in five regions including Hotan Xinjiang and Leshan Sichuan and Shanghai was carried out.Then a computation differentiation of Yin and Yang deficiency syndrome was done for the statistical analysis.Results Totally 5544 questionnaires were accomplished.In the five regions except Urumqi

the incidence of Yin and Yang deficiency syndrome in Xinjiang was higher than that of Shanghai and Sichuan（P<0.05）and the incidence in Hotan was higher than that of the other four regions（P<0.05）.The incidence in Uygur nationality was higher than that in Han nationality

the incidence in female higher than that in male

the incidence in middle aged people higher than that in youth

and the incidence in country higher than that in city.The difference was all significant in statistics（P<0.05）.In selected five regions with Urumqi not included

the incidence of Yin deficiency syndrome was the highest.Conclusion The incidence of Yin and Yang deficiency syndrome

especially the Yin deficiency syndrome

in Xinjiang is higher than that in the inner land.