The present invention relates to a method for diagnosing an allergy, comprising the steps of bringing basophils from a whole blood sample of a patient into contact with an allergen in an aqueous solution in the presence of whole blood, with a volume content of whole blood in the aqueous solution of at least 20 percent by volume, under conditions that allow activation of the basophils by the allergen, enrichment of the basophils from step a) and detection of activated basophils, wherein the detection is carried out in that the expression of a marker characteristic of activated basophils is detected by means of chemiluminescence; and a kit comprising a vessel for bringing the basophils into contact with the allergen, wherein the vessel is preferably a microtiter plate, optionally an allergen, an agent for detecting a marker characteristic of activat ed basophils by means of chemiluminescence, wherein the agent is preferably a ligand against the marker provided with a label capable of chemiluminescence and the ligand more preferably is a monoclonal antibody, optionally an agent for stopping activation of the basophils, an option ally immobilizable ligand that binds to a polypeptide located on the cell surface of basophils in dependently of its activation state, wherein the ligand is preferably a monoclonal antibody against the polypeptide, and optionally an agent for lysing and/orremoving erythrocytes.