This document specifies a method for the qualitative detection of the species-specific DNA of peanut (Arachis hypogaea), hazelnut (Corylus spp.), walnut (Juglans regia) and cashew (Anacardium occidentale) in food of animal and plant origin, using real-time PCR, in the context of allergen analyses. The method was previously validated in an interlaboratory study (ring trial) and applied to DNA extracted from samples that consist of defined proportions of peanut, hazelnut, walnut and cashew in rice biscuits, cooked sausage, sauce powder, vegan cookie and veggie burger (powder). The limit of detection of each real-time PCR has been determined experimentally to be about 5 mg/kg (10 mg/kg for roasted peanuts).