Androgen deprivation therapy (ADT) has been the first treatment for advanced prostate cancer. Although 90% of patients initially respond to ADT, the disease inevitably progresses to castration-resistant prostate cancer (CRPC). Docetaxel was reported to provide significant benefit over other chemotherapeutics in prolonging survival in CRPC. Recently, other chemotherapeutics have been used in cases where docetaxel is insufficient or the patient develops resistance, but yet their efficacy is limited. For this reason, it is necessary to develop docetaxel-based therapy, reduce toxicity, increase treatment efficiency. It has been shown that the non-toxic plant lectin Sambucus nigra agglutinin (SNA) drives ovarian cancer cells to the apoptotic pathway. Increased sialic acid levels in prostate cancer have suggested that SNA lectin, which binds to glycan sialic acid residues, may also have an activating effect on the apoptotic pathway for prostate cancer. In order to evaluate this, docetaxel and SNA were applied to DU-145 cells alone and in combination. Arterwards XTT cytotoxicity test, RNA isolation, cDNA synthesis, gene expression analysis by real time PCR method were performed. In our study, SNA alone did not show any effect on prostate cancer cells whereas it increased the efficacy of docetaxel. Furthermore, our study showed for the first time that SNA + docetaxel has a synergistic effect on the increase in Bim and decrease in Drp1expressions. Based on the data obtained from the current study, it is thought that the use of the SNA + docetaxel combination in the treatment of metastatic prostate cancer will increase the treatment efficacy.