Chestnut and chestnut-derived products are quite expensive and thus a possible target for fraudulent labeling. To obtain a French Label of Origin, chestnut producers need to certify the purity of their products. Chestnut-derived products are consumed by people who may suffer from celiac disease or are allergic to cereals. For these reasons, we developed a qualitative PCR-based method to detect cereal and leguminous species in chestnut flour. The presence of common wheat and barley was determined by amplifying part of the puroindoline-a gene, the presence of rye by amplifying part of the secaloindoline-a gene, the presence of durum wheat, rice, maize and chickpea by amplifying part of lipid transfer protein genes, the presence of oat by amplifying part of a thionin gene, the presence of kidney bean by amplifying part of a late embryogenesis- abundant protein, the presence of soybean by amplifying part of a lectin gene and the presence of fava bean by amplifying part of a nodulin gene. A chestnut thaumatine gene was used as control. PCR conditions were optimized to detect 1% of adulteration. Duplex PCR and specially designed sets of primers that allow amplification of several related species limited the number and cost of analyses required. Interpretation of the results is facilitated by using a decision tree