The aim of the study was to evaluate the effects of partial replacement of soyabean meal (SBM) with 35% of raw or fermented faba beans (RFB and FFB, respectively) on the development of the gastrointestinal tract and growth performance in young turkeys. FB were fermented with Lactobacillus plantarum. In comparison with RFB, FFB had similar crude protein content, but lower NDF and higher ADF contents. Partial replacement of SBM with FB seeds led to a decrease in wheat content, and an increase in the contents of highprotein components (by approx. 22 percentage points) and soyabean oil (by 2.5 percentage points) in turkey diets. The dietary inclusion of RFB and FFB did not affect the viscosity of small intestinal digesta. In comparison with the SBM diet, the RFB diet significantly decreased the concentrations of ammonia and butyric acid, reduced the activities of some microbial enzymes in the caecal digesta, but did not affect the concentrations of putrefactive and total short chain fatty acids (SCFAs). In comparison with the RFB diet, the FFB diet did not improve the turkey growth performance, but had a positive impact on fermentation processes in the caeca, which was reflected in an increase in the total concentrations of SCFAs and a decrease in ammonia concentration in the caecal digesta. So, dietary supplementation with 35% of FB does not compromise the growth performance of turkeys from 1 to 8 weeks of age. Fermentation of FB with Lactobacillus plantarum improves selected parameters of caecal functioning, but does not improve the growth performance of young turkeys.