Background/Aim. Plant polyphenols are well known to show antimutagenic, anticarcinogenic, antiviral and antioxi-dative activity. The aim of this study was to investigate bio-active potential of Armoracia rusticana root juice and extracts: their polyphenol content, as well as in vitro antitumor activity and cell-death mechanism. Methods. Liquid-liquid extrac-tion of polar and non-polar compounds was used and poly-phenolic compounds were identified and quantified by high performance liquid chomatography (HPLC) analysis. Anti-proliferative activity was examined in vitro on human cervix carcinoma (HeLa), breast adenocarcinoma (MCF7, MDA-MB-231), colon adenocarcinoma (HT-29), lung adenocarcinoma (A549), prostate adenocarcinoma (PC-3), melanocyte carcinoma (Hs 294T), hepatocyte carcinoma (Hep G2), as well as rat hepatocyte carcinoma (H-4-II-E), and normal human fetal lung (MRC-5) cell line using sulforhodamine B assay. The mechanism of cell-death in cell line was deter-mined using Cell Death Detection ELISAPLUS kit. Results. Dichloromethane extracts had the highest content of cate-chin, p-hydroxybenzoic, syringic and gallic acid (pulp, E1), and epicatechin (juice, E3). The results showed strong and non-selective antiproliferative activity of chloroform and di-chloromethane extracts and root juice – highest being to-wards liver, breast and lung tissue cells. IC50 values of ex-tracts and juice had low range of concentrations (IC50 = 3.49–26.5 μg/mL) and high range of dilutions (IC50 = 418–1,590). High and unfavorable potential of horseradish juice and chloroform juice extract (E4) to induce necrotic cell death was detected. Conclusion. Strong and non-selective in vitro antiproliferative activity of chloroform and di-chloromethane extracts and root juice of horseradish was detected, with necrosis as a main mechanism of induced cell death. In order to utilize horseradish root bioactive potential further investigations that will pinpoint active compo-nents with more favorable apoptosis/necrosis inducing properties are needed.