Feeding a diet containing 80% rye grain with a very high (7%) content of soluble dietary fibre to broiler chicks aged from 4 to 25 days resulted in severe damage of intestinal villi and the mucous membranes of the duodenum and small intestine. Similar changes were also observed in chicks receiving the rye diet with an addition of probiotics containing lactic acid bacteria. The addition of the antibiotic nisine at a rate of 2g/kg of the rye diet protected the intestinal villi. Nisine caused increase of feed intake and body weight gain without improving feed utilization. The rye diets, both with and without probiotics and nisine, did not induce changes in the amount and types of coliform, anaerobic or Gram ( + ) and Gram ( − ) bacteria in the faeces of chicks after 10 and 21 days of feeding as compared with initial level.