Just like in other stone fruits, also in peach trees, the Plum pox virus is commonly known to be the cause of lower yields, worse quality and smaller size of fruits and it also affects the contained substances. The fruits of peach trees infected with the Plum pox virus (PPV) were subjected to various analyses to determine the content of antioxidant activity and overall polyphenolic compounds. The evaluation took place from 2011 to 2012. To conduct this experiment, two cultivars that had been infected by PPV naturally were selected – ‘Royal Glory’ and ‘Symphony’. Antioxidant activity was established using five principally different methods (DPPH, ABTS, FRAP, DMPD and Free Radicals). The content of total polyphenolic compounds was established using the Folin-Ciocalteu method. The results of these analyses are expressed as the equivalent of gallic acid (GAE) in mg·kg−1. Furthermore, in the period from April to October the intensity of PPV symptoms in blossoms, leaves and fruits was also assessed.It was discovered that as a result of the PPV infection, the content of antioxidant activity as well as of total polyphenols had increased. Average reading of antioxidant activity in the PPV infected fruits had increased by 13.2 % (DPPH), 26.7 % (FRAP), 27.6 % (ABTS), 28.1 % (DMPD), 39.2 % (Free Radicals) and the content of polyphenolic compounds had gone up by about 30.4 % in comparison with the control varieties.