The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State Ireland, for the pesticide active substance fatty acids C7 to C18 are reported. The context of the peer review was that required by Commission Regulation (EC) No 2229/2004 as amended by Commission Regulation (EC) No 1095/2007. The conclusions were reached on the basis of the evaluation of the representative uses of fatty acids C7 to C18 as a herbicide, acaricide, insecticide or plant growth regulator on a variety of crops. The reliable endpoints concluded as being appropriate for use in regulatory risk assessment, derived from the available studies and literature in the dossier peer reviewed, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.