The present work shows the results of microscopy of Crataegus sanguinea Pall. leaves with flowers (Crataegi flores cum folia), which is considered as a perspective form of medicinal raw material, and the hypothetical plant adulterants – Amelanchier ovalis Medik., Prunus subgen. Cerasus (Mill.) A. Gray, Pyrus communis L., Aronia melanocarpa (Michx.) Elliott (Rosaceae). Parts of leaves and flowers of stated plants were subjected to anatomical investigation and comparative studies. Microscopical characteristics of leaves and flowers, which make possible to distinguish Crataegus from other species, were detected. The obtained data can be applied for the development of pharmacopoeial article “Crataegi Flores cum folia” for the XII edition of the Russian State Pharmacopoeia.