The EFSA Panel on Plant Health performed a pest categorisation of Diabrotica barberi (Coleoptera: Chrysomelidae), the northern corn rootworm, for the EU. D. barberi is a univoltine species occurring in mid-western and eastern USA and Canada, where it reproduces on maize (Zea mays), the preferred larval host. A small proportion of individuals can develop to a lesser extent on spelt (Triticum spelta), rice (Oryza sativa), millet (Panicum miliaceum) and a few North American wild grasses. Eggs are laid in the soil of maize fields, where they overwinter and can enter a diapause which can extend for more than one winter. Larvae hatch in late spring and early summer. Adult emergence peaks in the summer to feed on maize tassels, silks and ear tips. Adults abandon maize fields looking for other feeding hosts and return to maize for oviposition during late summer and autumn. D. barberi is considered a key pest of maize, together with other rootworm species of the same genus. D. barberi is regulated in the EU by Directive 2000/29/EC (Annex IAI). Within this Directive, a general prohibition of soil from most third countries prevents the entry of D. barberi larvae. However, adults carried on sweetcorn or green maize are potential pathways for entry into the EU. Climatic conditions and the wide availability of maize provide conditions to support establishment in the EU. Following establishment, impact on maize yields is anticipated. Phytosanitary measures are available to inhibit entry of this pest. D. barberi satisfies the criteria, which are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest. D. barberi does not meet the criteria of occurring in the EU nor plants for planting being the principal means of spread for it to be regarded as a potential Union regulated non-quarantine pest.