The study concerned nine assortments of multi-cereal breakfast flakes. Tests were performed to determine the content of dry mass, crude ash, crude proteins, crude fat, and crude fibre. The fractional composition of dietary fibre was determined with the detergent method (NDF, ADF, HCEL, CEL, ADL) and with the enzymatic method (TDF, IDF, SDF). Also, determinations were made of the content of soluble components of dry mass (WSI) and of the water absorption index (WAI). The multi-cereal assortments of breakfast flakes under study were characterised by a low protein content (5.33–9.78% d.m.), low content of dietary fibre TDF (5.03–10.21% d.m.), increased moisture and high content of soluble components of dry mass reaching up to 60%. Due to their poor chemical composition and high content of soluble components of dry mass, the tested assortments of breakfast cereals do not meet the requirements for cereal products of the base of the nutrition pyramid. Such products should definitely be classified among those of the top section of the pyramid.