It can be concluded that the environmental risk of Cu supplementation of diets of hens is marginal. The accumulation fo Cu in soil and herbage was limited even at the highest concentration of u in the feed. A moderatesupplementation of hen diets with Cu,and fertilization of soil with hen excreta may increase Cu concentration in herbage to a desirable level. The highest permissible concentration of Cu in diets for poultry might be increased. Because of Cu mobility in soil, however, Cu originated form poultry excreta may contaminate surface and ground water. This feature of poultry manure land application requires further study.