Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on l-tryptophan produced by fermentation using Escherichia coli KCCM 80135 when used as a nutritional additive in feed and water for drinking for all animal species. The production strain and its recombinant DNA were not detected in the additive. l-Tryptophan produced by fermentation with E. coli KCCM 80135 does not raise any safety concern with regard to the genetic modification of the production strain. The use of l-tryptophan produced using E. coli KCCM 80135 in supplementing feed to compensate for tryptophan deficiency in feedingstuffs is safe for non-ruminant target species. Using unprotected forms of tryptophan in ruminants can be a risk. The use of l-tryptophan produced by fermentation using E. coli KCCM 80135 in animal nutrition presents no safety concerns to consumers of animal products. l-Tryptophan produced by E. coli KCCM 80135 is not toxic by inhalation. The additive is not an irritant to skin and eyes, and it is not a skin sensitiser. The additive under assessment is considered safe for the environment. It is regarded as an effective source of the amino acid l-tryptophan for all non-ruminant species. If the additive l-tryptophan is intended for use in ruminants, it should be protected from ruminal degradation.