Individual symptoms of allergy such as asthma, dermatitis, rhinitis have many different underlying mechanisms. The detailed characterization of the inflammatory mechanisms underlying symptom development in the individual patient is important in order to optimally control treatment. Measurement of eosinophil cationic protein (ECP) in sputum or blood and eosinophil protein X/eosinophil derived neurotoxin (EPX/EDN) in urine may be used to read the involvement of the eosinophil granulocyte in the process. An important information as eosinophil dominated processes seem to be particularly sensitive to corticosteroid treatment. The possibilities to measure the involvement of other inflammatory cells exist today, but are only used to a small extent. The dream would be that every patient with an inflammatory disease is characterized with respect to the profile of involving cells and mediators. Such information would provide us with a unique understanding of the underlying mechanisms of the development of disease symptoms and the possibilities of treating these.