The term "phytogenics", also referred to as botanicals or phytobiotics, describes plant-derived compounds incorporated in animal feed to improve productivity of livestock through amelioration of feed properties and promotion of the animal's production performance. In the last few years phytogenics have gained considerable attention in the feed industry. The in vitro antimicrobial, antiviral, antifungal, antioxidant and other activities of phytogenic compounds are well described and backed up by numerous scientific reports. In the meanwhile, an increasing number of studies addressing the gastro-intestinal effects of phytogenics under in vivo conditions in animal feeding experiments are available. The application of this new type of feed additives in different animal species is reviewed by international experts.