This paper is aimed to select plant materials rich in bioflavonoid compounds, made from herbs known for their application performances in the prevention and therapy of renal diseases, namely kidney stones and urinary infections (renal lithiasis, nephritis, urethritis, cystitis, etc.). This paper presents a comparative study of the medicinal plant extracts composition belonging to Ericaceae-Cranberry (fruit and leaves) - Vaccinium vitis-idaea L. and Bilberry (fruit) - Vaccinium myrtillus L. Concentrated extracts obtained from medicinal plants used in this work were analyzed from structural, morphological and compositional points of view using different techniques: chromatographic methods (HPLC), scanning electronic microscopy, infrared, and UV spectrophotometry, also by using kinetic model. Liquid chromatography was able to identify the specific compounds of the Ericaceae family, present in all three extracts, arbutosid, as well as specific components of each species, mostly from the class of polyphenols. The identification and quantitative determination of the active ingredients from these extracts can give information related to their therapeutic effects. (C) 2015 Elsevier B.V. All rights reserved.