The objective of this study was to investigate the effects of a mixture of dried pulps of Daucus carota L., aerial parts of Echinacea purpurea L. Moench, sawdust and extracts of Larix decidua Mill., all industrial waste, as feed additive in different concentrations (3 % and 5 % of the diet) for the prophylaxis of E. coli-diarrhoea in weaner piglets. For phytochemical characterization of the feed additive, the total phenolic content was determined in each component of the mixture. Prevalence of diarrhoea was evaluated by a diarrhoea score modified according to DIEU (2006). Diarrhoea appeared less frequently in the additive groups than in the control group. The number of diarrhoea cases and the duration of diarrhoea per case were lowest in the 3 % group. E. coli and haemolysing E. coli were determined quantitatively in the faeces on day of weaning and on day 6 after weaning. The body mass did not differ significantly (p > 0.05) between the groups although a tendency to a higher mean-body mass was found at the end of the trial in the 3 % and 5 % additive groups. The piglets of the 3 % group showed the highest feed intake whereas the piglets of the 5 % group displayed the best feed conversion ratio. Blood parameter levels (white blood count, UREA, GGT, AST, TP and haptoglobin) were within the normal range except for AST-activity, which exceeded the threshold value in all groups. Statistical evaluation of the blood parameters showed no significant differences between the groups. Haptoglobin increased in the first week after weaning.