Himalayan balsam, Impatiens glandulifera Royle, and Balfour’s touch-me-not, Impatiens balfourii Hooker f., are invasive weeds that are threatening habitat diversity in many European countries, including Croatia. Various bioactive secondary metabolites from species of genus Impatiens L. have been reported and some species are traditionally used as herbal medicines. Th e aim of this research was to determine total polyphenol (TP) and total fl avonoid (TF) content, as well as antioxidant activity of leaves and fl owers of species I. glandulifera and I. balfourii. Spectrophotometric methods were used to obtain TP, TF content and inhibition of 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals to measure antioxidant activity. Total polyphenol quantity ranged from 7.9 to 18.6 mg equivalent of gallic acid per g of dried plant material, while total fl avonoid content ranged from 4.6 to 20.5 mg equivalent of quercetin per g of dried plant material. Leaves of I. glandulifera contain more polyphenols than fl owers of the species (18.5 vs. 13.1 mg EGA/g DPM) but less fl avonoids comparing to fl owers (5.7 vs. 8.3 mg EQ/g D PM). However, in the case of I. balfourii both polyphenols and fl avonoids are more abundant in fl owers and have the highest quantity of polyphenols and fl avonoids overall (18.6 mg EGA/g DPM and 20.5 mg EQ/g DPM). Both TP and TF content showed no signifi cant correlation with antioxidant activity, except in the case of TP and DPPH test where correlation was found (r=0.67). Despite diff erences in phenolics, fl owers of I. glandulifera exhibit the highest antioxidant activity in both tests, 3.8 and 3.8 mg EGA/g DPM, for DPPH and ABTS test respectively. In sum, fl owers seem to possess higher quantity of antioxidant compounds than do leaves in case of both species.