A study was conducted on the effect of the process of extrusion on changes in dietary fibre fractional composition. The material used in the study comprised a blend of corn grits, oat bran, everlasting pea wholemeal and powdered whole milk. The process of extrusion was conducted in a single-screw extruder, at the following parameters: L:D=12:1, screw compression ratio of 3:1, die diameter of 3.5 mm, screw speed of 110 rev. min-1, cylinder temperature profile of 145/165/120°C. Raw material moisture content was adopted as 13.5%, and the relative share of oat bran, everlasting pea wholemeal and powdered whole milk was variable. The introduction of oat bran and everlasting pea wholemeal in the blends permitted obtainment of extrudates with increased content of dietary fibre, especially of its soluble fraction. The additives applied allowed also to obtain extrudates with low values of water solubility index. As a result of the process of extrusion, a lowering of the content of total dietary fibre and its insoluble fraction, and an increase in the content of the soluble fraction were observed in the extrudates. Changes in the fractional composition of dietary fibre were related primarily to the composition of the raw material blends.