The current use of antibiotics in weaner pig diets is likely to be banned from 2006, and alternatives are sought to improve growth and health status of weaner pigs. Hops (Humulus lupulus L.) are mainly known from the brewing industry, but they are also known for their antimicrobial activity and antioxidant properties (Stevens et al., 1998). Hops may be a suitable alternative to antimicrobial growth promoters, particularly when pigs are not able to maximise their growth potential, for example when fed low density rations. The objective of the trial was to investigate the effects of hops on newly weaned piglets on growth performance, liver function and microbiology in diets of different nutrient density.