The aim of this study was to investigate the influence of standardized Epilobium angustifolium L. extract [100 mg/kg/day, p.o.] on the expression level of 5α-reductase type 2 (Srd5ar2) mRNA and Mapk3 mRNA a representative of non-genomic xenobiotics signaling pathway. It was shown that plant extract from the E. angustifolium showed a slight tendency to reduce prostate weight in hormonally induced animals (p>0.05) and in testosterone induced animals receiving both, extract and finasteride (p<0.05). Finasteride in rats induced by testosterone caused a smaller decrease in the level of mRNA 5α-steroid reductase 2 (SRd5ar2), than in rats treated with the hormone and studied plant extracts. In general, an increase in the amount of MAPK3 mRNAs in testosterone-induced groups of rats receiving tested plant extract with or without finasteride was observed, while the expression of type 2 5α-steroid reductase decreased (p<0.05). Further experimental studies should be performed in order to understand the molecular basis of interactions, the efficacy and safety of tested plant extracts.