Abstract: Objective To ascertain pathogenic ingredients in cosmetics resulting in dermatosis in Changning District of Shanghai. Methods By means of questionnaire,a survey was done among volunteers,with the history of unwelcome cosmetic reactions in ten communities of Changning District of Shanghai.They received cosmetic series diagnostic patch test. Results Of a total of 122 volunteers,34 were observed with positive reactions, the positive rate being 27.87%.The top five antigens in positive rates were Shellac,Thimerosal, Methylisothiazolinone + Methylchloro-isothiazolinone,Dodecyl Gallate,and Sorbitan Sesquioleate.Meanwhile,The top five different categories of antigens in positive rates were preservatives,colorants,emulsifying agent,antioxidant and surfactant.There were no significant differences found between genders and ages. Conclusion Patch test is an important basis for diagnosis of cosmetic dermatosis.By large sample investigation,common cosmetic pathogenic ingredients in Shanghai can be determined.Then,pathogenic database can be established,which is important in active prevention of cosmetic dermatosis.