Abstract: From September 1980 to 1981, the authors investigated A5 factories in Shanghai, in which epoxy resins were used or manufactured. Through the investigation 36 patients with dermatitis were discovered in 13 factories, the average incidence was 13%.The cutaneous manifestations were predominantly those of allergic contact dermatitis, By analysing the data from the patients and experimental animals it was show that epoxy resins are contact sensitizers and the sensitizing capacity varies with their molecular weight. The authors suggested that some kinds of hardeners used in these factories are highly irritant and may thus enhance the developemeat of epoxy resin dermatitis.