Rifampin, when given in usual doses, is well tolerated with less than 4% of patients having significant adverse reactions. The patient had did not have any adverse reaction to rifampin in the first place. After 10 years, however, the patient was presented with hypotension, shortness of breath, wheezing and deterioration of consciousness in 10 minutes after taking rifampin. All abnormal symptoms and signs of anaphylaxis were normalized in 24 hours after administration of normal saline, glucocorticosteroid, and antihistamine. Skin prick test with rifampin showed positive reaction to gradual concentration of rifampin in dose dependent manner. The wheals by rifampin developed in 30 minutes and maximized in 2 hours, while normal saline and histamine controls showed expected negative and positive response in 10 minutes, respectively. Recently we expererienced a rare case of anaphylaxis after single oral administration of rifampin(450mg), who had been treated with antituberculous drug including rifampin, ca 10 years ago.