The analysis of mucosa proteomes was performed using a twodimensional electrophoresis combined with mass spectrometry to determine the effect of dietary level of inulin on protein expression patterns in the ileum. The experiment was carried out on 24 castrated male piglets, allocated to three groups, fed from the day 10 of life an unsupplemented diet (C) or diet supplemented with 1% (T1) or 3% (T2) of native chicory inulin. Samples of ileal tissue and blood were collected after 40 days of feeding. Comparative proteomic analysis of the T1 group showed 10 protein spots with a decreased expression, whereas the T2 diet caused overexpression of 24 spots in comparison to the C diet. Inulin levels differed in their effects on the expression of ileal proteins involved in intracellular molecular mechanisms controlling cell division and growth. The T1 diet down-regulated, whereas the T2 diet induced substantial up-regulation of proteins engaged in transcriptional and translational activities, folding and posttranslational modifications, which may indicate stimulation of epithelial cell proliferation. Inulin did not affect plasma levels of phosphorus, magnesium, calcium and iron in piglets but improved plasma prooxidant-antioxidant balance in animals fed the T2 diet. The results of this study might be considered as preliminary since further confirmation using more sophisticated quantitative proteomic tools is required to better understand and answer the unresolved issues concerning the mechanism underlying the inulin effect on the ileum in growing pigs. Nevertheless, a general insight into how inulin molecules or their fermentation end-products may induce changes in protein expression patterns in the ileum was presented.