In June 2005, the work of the EU Integrated Project EuroPrevall was started. EuroPrevall is the largest research project on food allergy ever performed in Europe. Major aims of the project are to generate for the first time reliable data on the prevalence of food allergies across Europe and on the natural course of food allergy development in infants. Improvement of in vitro diagnosis of food allergies is another important aim of the project. The present review summarizes current knowledge about the clinical presentation of food allergy and critically reviews available diagnostic tools at the beginning of the project period. A major problem in diagnosis is a relatively poor 'clinical specificity', i. e. both positive skin tests and in vitro tests for specific IgE are frequent in sensitized subjects without food allergy symptoms. So far, no in vitro test reliably predicts clinical food allergy. EuroPrevall aims at improving the predictive value of such tests by proceeding from diagnosis based on allergen extracts to purified allergen molecules, taking into account the affinity of the IgE-allergen interaction, and evaluating the potential of biological in vitro tests such as histamine release tests or basophil activation tests including assays performed with permanently growing cell lines.