Acetylsalicylic acid, commonly known as aspirin, can induce some hypersensitive reactions with clinical symptoms such as urticaria, angioedema, acute bronchospasm, and rarely anaphylactic shock. At present, detection of aspirin allergy is still rather difficult and requires an adequate clinical history and sensitive in vivo and in vitro tests. The aim of the study was to evaluate the diagnostic utility of cellular antigen stimulation test (CAST) in the detection of allergic reaction mediated by aspirin. Fifty patients (39 women and 11 men) with a history of hypersensitivity reaction to aspirin were included in the study. Positive scratch test to aspirin was found in 72% (36/50) and positive CAST in 58% (29/50) of patients. Both skin scratch test and CAST positive results were recorded in 48% (24/50%) and negative results in 20% (9/45) of patients. The level of agreement between skin scratch test and CAST was fair with Cohen's kappa of 0.269 (0.95% CI 0.004-0.533). The observed between-test agreement was 66%. It is concluded that CAST-ELISA might be of value as an additional test for the detection of aspirin nonallergic hypersensitivity in suspected individuals.