The objective of the present study was to evaluate the effects of fibre source on intestinal mucosal barrier function in weaning piglets. A total of 125 piglets were randomly allotted on the basis of their body weight and litters to one of five experimental diets, i.e. a control diet without fibre source (CT), and diets in which expanded maize was replaced by 10% maize fibre (MF), 10% soyabean fibre (SF), 10% wheat bran fibre (WBF) or 10% pea fibre (PF). The diets and water were fed ad libitum for 30 d. Piglets on the WBF and PF diets had lower diarrhoea incidence compared with the MF- and SF-fed animals. A higher ratio of villous height:crypt depth in the ileum of WBF-fed piglets and higher colonic goblet cells in WBF- and PF-fed piglets were observed compared with CT-, MF- and SF-fed piglets. In the intestinal digesta, feeding WBF and PF resulted in increased Lactobacillus counts in the ileum and Bifidobacterium counts in the colon. Lower Escherichia coli counts occurred in the ileum and colon of WBF-fed piglets than in SF-fed piglets. Tight junction protein (zonula occludens 1; ZO-1) and Toll-like receptor 2 (TLR2) gene mRNA levels were up-regulated in the ileum and colon of pigs fed WBF; however, feeding MF and SF raised IL-1α and TNF-α mRNA levels. Furthermore, higher diamine oxidase activities, transforming growth factor-α, trefoil factor family and MHC-II concentration occurred when feeding WBF and PF. In conclusion, the various fibre sources had different effects on the ileal and colonic barrier function. Clearly, WBF and PF improved the intestinal barrier function, probably mediated by changes in microbiota composition and concomitant changes in TLR2 gene expression.