OBJECTIVES: Inulin is a plant polysaccharide that may affect the gut barrier depending on its degree of polymerization (DP). Therefore, this study aimed to determine the effect of dietary level of two inulin types differing in DP on mucin content and MUC gene expression in the colon mucosa of pigs. METHODS: The 40-d experiment involved 56 piglets divided into seven groups fed a diet with 0%, 1%, 2%, or 3% inulin with DP of 10 or 23. Mucin content was measured fluorometrically, gene expression was determined by quantitative polymerase chain reaction, and data were analyzed by one-way analysis of variance and three-way analysis of variance. RESULTS: In the proximal colon, mucin content was decreased by the diet with 1% inulin with DP of 23 (IN23), whereas in the middle colon mucin content was decreased by the other IN23 diets. The diet with 3% inulin with DP of 10 upregulated MUC2 and MUC12 in the proximal colon and MUC2 and MUC13 in the middle colon. In the proximal colon, all IN23 diets increased MUC2 expression, whereas the 2% and 3% IN23 diets upregulated MUC1 and MUC12. In the middle colon, MUC2 was increased by the 1% and 2% IN23 diets, MUC4 by the 1% diet, and MUC13 by the 3% diet. In the distal colon, the 3% IN23 diet upregulated MUC1, whereas all IN23 diets downregulated MUC2, MUC4, and MUC12. With the exception of MU13 and MUC20, the expression of MUC genes was the highest in the proximal colon. CONCLUSIONS: Inulin, particularly with higher DP, may exert a beneficial effect on the colon mucosa by modulation of MUC gene expression.