Drug hypersensitivity can occur with almost any drug and may range widely in clinical severity from mild pruritus, acute urticaria or angioedema to life-threatening anaphylaxis. Affected patients usually avoid the suspected drug in the future, but in selected cases the particular drug is essential for optimal therapy due to unavailable or ineffective alternative therapy. Under these circumstances, desensitization may be performed. Desensitization protocols have been developed and are used for antibiotics, sulfonamides, non-steroidal antiinflammatory drugs, insulins, biologic agents, and many others. Desensitization procedure is based on the induction of a temporary state of tolerance of a substance responsible for a hypersensitivity reaction. Gradually increasing doses of the drug are administered to the patient over several hours to a few days, until the total cumulative therapeutic dose is achieved and tolerated. Hypersensitivity to acetylsalicylic acid is a common indication to desensitization in a daily practice. A few protocols for this drug have been described. Recently, 7 patients hypersensitive to acetylsalicylic acid have been desensitized in our department due to cardiologic and rheumatologic reasons. In this group, desensitization procedures were performed successfully and the patients could continue pharmacotherapy with aspirin.