In order to continue our previous studies concerning Geranium robertianum L., herb Robert (Geraniaceae), we have realised a HPLC study of some polyphenols using an original method created by a group of young researchers from the University of Medicine and Pharmacy of Cluj-Napoca. We have identified and measured in the dried Geranii robertiani herba (harvested from Valea Runcului, district of Alba-Iulia) the following compounds: hyperoside (3.64 microg/100 mg), ellagic acid (7599.76 microg/100 mg), isoquercitrin (49.49 microg/100 mg), quercetrin (83.92 microg/100 mg), kaempferols (143.43 microg/100 mg), caftaric acid (166.92 microg/100 mg), rutoside (72.23 microg/100 mg). We have also analysed a hydrolysed sample of the same drug in which we have identified and measured: caffeic acid (6.62 microg/100 mg), ellagic acid (10550.65 microg/100 mg), quercetrin (203.44 microg/100 mg), kaempferols (231.80 microg/100 mg), caftaric acid (47.41 microg/100 mg). We have indirectly proved the presence of ellagic tannins (the amount of ellagic acid increases after acid hydrolise) and the existence of bi- or polycaffeoil derivatives (the caffeic acid is present only in the hydrolysed sample). The flavonoid aglycones exist in both forms: as free compounds and as part of the flavonoid molecules.