Following a request from the European Commission, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of nine compounds belonging to chemical group 28 (pyridine, pyrrole and quinoline derivatives). They are currently authorised as flavours in food. The FEEDAP Panel concludes that piperine, 3-methylindole, indole, 2-acetylpyridine and 2-acetylpyrrole are safe at the proposed maximum use level of 0.5 mg/kg complete feed for all animal species; trimethyloxazole, 3-ethylpyridine, pyrrolidine and 2,6-dimethylpyridine are safe at the proposed use level of 0.5 mg/kg complete feed for cattle, salmonids and non-food-producing animals, and at the use level of 0.3 mg/kg complete feed for pigs and poultry. No safety concern would arise for the consumer from the use of these compounds up to the highest safe level in feeds. Hazards for skin and eye contact, and respiratory exposure are recognised for the majority of the compounds under application. Most are classified as irritating to the respiratory system. The concentrations considered safe for the target species are unlikely to have detrimental effects on the terrestrial and fresh water environments. As all the compounds under assessment are used in food as flavourings, and their function in feed is essentially the same as that in food, no further demonstration of efficacy is necessary. In the absence of data on the stability in water for drinking, the FEEDAP Panel is unable to conclude on the safety or efficacy of the substances under this mode of delivery.