A case is described where piglets reacted with severely reduced feed intake, watery and dark faeces, poor growth and rough hair coat after delivery of a new charge of a commercial pelleted diet. Body temperature was normal, the behaviour appeared depressed. The diet contained 860 mg copper/kg, which was highly above the labelled concentration (160 mg/kg) and the concentration allowed by feed legislation (175 mg/kg for pigs up to 16 weeks of age). After changing to a new mixed feed the general condition of the piglets improved and faecal consistency and colour normalised within a few days.