Abstract The aim of this study was to investigate the influence of standardized crude aqueous Epilobium angustifolium L. extract [100 mg/kg/day, p.o.] on the expression level of SRC kinase mRNA - a representatives of non-genomics xenobiotics signaling pathway in prostate ventral lobes of testosterone-induced, castrated rats. We have shown that in all analyzed groups induced by testosterone an elevation of SRC kinase mRNA transcription was observed, in comparison to control animals (not receiving the testosterone), (p<0.05). Finasteride in rats induced by testosterone caused the strongest inhibition of SRC mRNA transcription (p<0.05). In rats receiving testosterone and the plant extract a ca. 90% decrease of mRNA level was observed vs. testosterone-induced animals (p<0.05), while in testosterone-induced animals receiving concomitantly E. angustifolium extract and finasteride the observed reduction reached 87.3% (p<0.05). We did not observed, however, any positive feedback between studied plant extract and finasteride in the inhibitory activity (p<0.05). Further experimental studies should be performed in order to the understanding the molecular basis of interactions, the efficacy and safety of tested plant extract.