Abstract Liderfeed® is a zootechnical feed additive containing eugenol as active ingredient with some excipients. It has not been authorised in the European Union for use in food or feed. Liderfeed® was initially formulated with clove oil as a source of eugenol. The applicant replaced the clove oil with purified eugenol at the same concentration as in the original formulation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) considered that studies carried out using the original formulation and the subsequently modified formulation are equivalent. The FEEDAP Panel concluded that Liderfeed® is safe for chickens for fattening at the proposed dose of 100 mg/kg complete feed. The addition of Liderfeed® at the recommended dose did not result in measurable concentrations of eugenol and its glucurono‐ and sulpho‐conjugates in edible tissues. Liderfeed® is therefore considered safe for the consumer when used as an additive in feed for chickens for fattening. Liderfeed® is not considered to be a skin/eye irritant or a skin sensitiser. The exposure of users by inhalation is expected to be low. The use of Liderfeed®in feed for chickens for fattening can be considered safe for the environment. As only two out of the three efficacy studies showed a significant effect on the performance of chickens for fattening as a result of the supplementation with the additive, the FEEDAP Panel was unable to conclude on the efficacy of Liderfeed® in chickens for fattening. Dietary supplementation with Liderfeed® did not adversely affect chicken meat quality.