Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of ferrous lysinate sulfate as nutritional feed additive for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed ( FEEDAP) Panel was assigned to this mandate. Based on the results of a tolerance study, the FEEDAP Panel concluded that ferrous lysinate sulfate is safe in chickens for fattening when used up to the current maximum authorised levels of total iron in feed; this conclusion was extrapolated to all animal species and categories, at the respective maximum authorised iron levels in complete feed. The use of ferrous lysinate sulfate in animal nutrition up to the maximum iron content in complete feed authorised in the EU poses no concern to the safety of consumers. The FEEDAP Panel concluded that ferrous lysinate sulfate poses a risk to users by inhalation; the additive is not a dermal irritant, but is irritant to eyes and a skin sensitiser. The FEEDAP Panel considered that the use of ferrous lysinate sulfate in animal nutrition would not pose a risk for the environment. Owing to the limitations in the study provided, the FEEDAP Panel could not conclude on the efficacy of the additive for chickens for fattening, and thus, on the efficacy of ferrous lysinate sulfate for all animal species and categories.