Intolerance or idiosyncrasy to acetylsalicylic acid (ASA) and other nonsteroidal anti-inflammatory drugs (NSAIDs) is a crucial problem because these drugs are frequently used in medical treatment. In this study, we tested whether nimesulide, a selective cyclooxygenase-2 (COX-2) inhibitor, might be a valid alternative for patients with histories of adverse reaction to ASA or NSAIDs. A single-blind, placebo-controlled oral challenge procedure was applied to 60 adult patients (19 male, 41 female; with a mean age of 40.31 +/- 10.44 years, range 20-68 years) with a reliable history of ASA/NSAIDs-intolerance. According to history, the clinical presentations of intolerance were urticaria/angioedema in 32 patients, anaphylactoid reaction in 2 patients, respiratory reaction in 19 patients, and respiratory and cutaneous reaction in 7 patients. Atopy was confirmed by means of skin prick test with inhalant allergens. Oral challenge protocol was started with 25 mg of nimesulide and the remaining 75 mg was given 1 hr later. During the challenge procedure, blood pressure, pulse, nasoocular, pulmonary, and cutaneous symptoms were monitored. Of the 60 patients tested, 55 (91.7%) tolerated the drug with no adverse reaction. Only five (8.3%) patients demonstrated a positive response to oral challenge. The clinical presentations of intolerance to nimesulide were urticaria/angioedema in three patients, mild rhinitis in one patient, and mild dyspnea in one patient. The atopy prevalence was higher, with a ratio of 41.7%, in patients with ASA/NSAIDs intolerance than that of the healthy adult population in Turkey (p < 0.05). We believe that nimesulide can be used as an alternative drug for patients with ASA/NSAIDs intolerance.