The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessment carried out by the competent authority of the rapporteur Member State the United Kingdom, for the pesticide active substance dimethoate are reported. The context of the peer review was that requested by the European Commission following the submission and evaluation of confirmatory mammalian toxicology, residues and ecotoxicology data. The conclusions were reached on the basis of the evaluation of the representative uses of dimethoate as an insecticide on sugar beet and protected lettuce. Concerns are identified. (C) European Food Safety Authority, 2013