The aim of the study was to investigate the effect of dietary levels of wheat gluten (WG) protein on the ileal flow of crude mucin and sugars, as well as sugar composition of crude mucin preparations in young pigs. Six cannulated young pigs were used in 3 periods × 3 diets in the Latin square design. The three isoenergetic diets containing low, medium or high WG protein level (LWG, MWG and HWG, respectively) were formulated. LWG diet was treated as a control. The three dietary WG levels were obtained by supplementing 26.7, 52.9 and 79.0 g WG/kg to the respective diets. Ileal digesta was collected during the last 3 days of each 7-day period. Xylose content in ileal digesta was higher in LWG pigs compared to two other pigs groups. Galactose content was higher in MWG pigs compared to LWG and was lower compared to HWG pigs. Xylose content decreased linearly and galactose content increased linearly with increasing dietary WG protein levels. The HWG diet increased ileal flow of crude mucin and galactose compared to the LWG diet. The flow of crude mucin and galactose increased linearly with increasing dietary WG protein levels. The content of galactose in crude mucin preparations was higher in MWG pigs than in LWG pigs and was lower than in the HWG pigs. Dietary WG protein levels had a linear effect on the content of xylose and galactose in crude mucin preparations. In conclusion, WG protein positively affected ileal flow of mucin and its sugar composition.