There are already many reports in various allergic reactions by aspirin, but most of them deal with the reactions induced by aspirin alone or a physical compound of aspirin and serum protein, as the antigens. For this reason they failed to demonstrate the antigen-antibody reaction in vitro although they recognized the establishment of active allergy. In addition, there are few reports in which conjugates of aspirin to serum proteins are used as antigen, but there seems to be no report on any experimental localized passive allergy. In the present experiment, the author selectively sensitized rabbits and guinea-pigs using conjugates of aspirin to proteins or aspirin solutions as the antigens, and studied the localized skin allergy in these te...