Abstract: Ojbective: To study more frequent sensitizers and relationship between sex and allergens by analyzing results of patch testing 1,129 suspected allergic contact dermatitis（ACD） patients in department of Dermatology in PLA General Hospital from July 2005 to July 2006,and to provide a clue for prevention and cure for ACD and selection of allergens used in diagnosis in the area.Methods: Suspected ACD patients were patch tested with a modified European standard series of allergens.Results: Among 1129 patients,747 had positive patch test reactions.Nickel sulfate was the most frequent sensitizer,followed by Thimerosal,Potassium dichromate,Fragrance mix and Formaldehyde.Frequencies of contact allergy to Thiuram mix,Mercapto mix,Imidazolidinyl urea,and bronopol were relatively low.Positive reactions to nickel sulfate were more frequently observed among women.Men had a higher frequency of positive reactions to Carba mix.The difference in nickel and Carba mix sensitization rates between women and men was statistically significant（P＜0.001）.Conclusion: Nickel sulfate,Thimerosal（merthiolate）,Potassium dichromate,Fragrance mix and Formaldehyde are more frequent sensitizers in the area.Reactions to nickel sulfate and Carba mix are different between men and women.it is effective and safe to patch test suspected ACD patients.