To identify and characterize aspirin sensitivity, over 500 oral aspirin challenges have been performed in patients since 1970. Protocols were developed, and an aspirin desensitization process was created as an extension of the challenge protocol. Without exception, desensitization has been achieved in 66 of 66 consecutive aspirin-sensitive asthmatics. There is also cross-desensitization with nonsteroidal anti-inflammatory drugs (NSAIDs) in the limited number of patients studied. After desensitization with either aspirin or NSAIDs, an interruption of continuous therapy is followed by a reappearance of sensitivity. Patients must be cautioned about this and the possibility of a severe reaction should aspirin be reintroduced after aspirin avoidance for 2-5 days.