The stomach contents of the Atlantic Horse Mackerel. Trachurus trachurus (Linnacus, 1758), were analysed to investigate the food and feeding habits of this species with respect to fish size and season. A total of 60 different prey species was found belonging to five major systematic groups, i.e. Polychaeta, Crustacea, Mollusca, Chaetognatha and Osteichthyes. Crustaceans (especially Copepoda, Euphausiacea and Mysidacea) were the most important food category by percentage of relative importance index. Telcosts were the second most important food category, while Polychaeta and Chaetognatha were occasionally seen as trod. Little seasonal variation in the diet of T trachurus was observed: copepods and mysids were the dominant prey groups in all seasons, and telcosts except in spring were the most frequent prey. However, differences in size were highlighed, with fish larger than 16.9 cm feeding on telcost larvae. At least 45 Copepoda species were identified, with Acartia clausi and Oncea media being the most significant among them by the percentage of relative importance index groups in all seasons. Copepods, euphnusiids and mysids were thus the most important prey to be consumed by Trachurus trachurus in all seasons as well as by the small size classes. Moreover, telcosts constituted the main food for larger specimens.