The effect of feeding diets containing 10% of either cellulose, or apple pulp, pectin, sugar beet pulp, or potato pulp, on preprandial and postprandial changes of plasma concentration of glucose and insulin, and on the cholesterol level 8 h after the meal, were determined in pigs of 39 kg body weight. Glucose and cholesterol concentrations were not affected by the type of fibre. The insulin concentration shortly after the meal was the highest in pigs fed on potato pulp and the lowest on cellulose, while 45 and 60 min postprandially, it was higher on pectin than on other fibre sources.