Rubus fruticosus L. is a shrub famous for its fruit called blackberry. It is naturalized throughout most of the world and has been extensively used in herbal medicine from time immemorial.The leaves and fruits contain numerous phytochemical including polyphenols, flavonoids, tannins, anthocyanins, salicylic acid, ellagic acid, and fiber. The plant raw material consisted of dried blackberry leaves of the Arapaho variety, harvested from the collection of SPCFMP. The extracts were obtained with 70% ethanol by maceration with stirring and concetration of on the rotative evaporator. The total content of hydroxycinnamic acids was measured in dried extract by spectrophotometric method, with Arnow’s reagent. Antioxidant activity of the dry extract was determined by DPPH method. The total of hydroxycinnamic acids, expressed in caffeic acid, in dried blackberry leaves was 0,83%, and in the dried extract was determined in ten times more 8,02%. The dried extract of blackberry leaves showed high radical scavenging activity (IC50 = 11.46%), compared to the Trolox (IC50 = 3.15%) reference substance. This study showed that blackberry leaf extract with a high content of hydroxycinnamic acids, can be used as a natural antioxidant and antimicrobian for medical purposes. This study was supported by project from State Program: “Biological and phytochemicalstudy of medicinal plants with antioxidant, antimicrobial and hepatoprotective action”, nr.20.80009.8007.24.