The labeling of 5 major allergenic ingredients (egg, milk, wheat, buckwheat, and peanut) is mandatory in Japan, and 2 series of enzyme-linked immunosorbent assay (ELISA) kits have been established as official screening methods. However, these official methods have not provided the necessary sensitivity, due in part to poor extraction efficiency. To address this need, 2 novel ELISA kits have been developed: the FASTKIT ELISA Ver. II Series and the FASPEK Allergenic Substances Detection Kit. The new kit systems use an improved extraction buffer that can extract insoluble proteins produced by processing and feature new antibodies that bind to the denatured proteins extracted with the new extraction buffer. The analytical performances of the 2 new ELISA kit series were evaluated in an interlaboratory study. Ten laboratories participated in the study and determined the major allergenic ingredients contained in 5 types of model processed food. The 2 ELISAs displayed fairly good reproducibility and sufficient recovery.