The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Hungary, and co‐rapporteur Member State, the Netherlands, for the pesticide active substance Purpureocillium lilacinum strain 251, formerly called Paecilomyces lilacinus strain 251, are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of Purpureocillium lilacinum strain 251 as a biological nematicide on tomato and cucumber (uses in the field and permanent greenhouses). The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.