Walnuts are potent inducers of food allergic symptoms. So far, five allergens were identified, among those, Jug r 2 belonging to the vicilin family. Based on the identification of an IgE-reactive clone from a cDNA library in 1999 (Teuber et al.), the sequence fragment of Jug r 2 was determined. However, only limited data is known about the natural form of the protein. Therefore, this study aimed to purify and characterize the natural Jug r 2. During the study we identified another vicilin with both, higher sequence identity to vicilins from related species and IgE cross reactivity as compared to Jug r 2.