Objetives. This study aimed to research the in vitro immunomodulatory effects of an Uncaria tomentosa hydroalcoholic extract standardized (5.03%, pentacyclic oxindole alkaloids) (UT-POA) on the immunophenotype of dendritic cells (DC) subsets, Th1, Th2, Th17 and IL-12 cytokines from patients with stage II breast cancer (BCII) and healthy women (H). Materials and methods. Blood of 11 H and 7 BCII was obtained, PBMC were isolated and cultured for 2h with/without various concentrations of UT-POA and stimulated or not with LPS for 24h. PBMC were labeled with specific antibodies for DC and in the supernatant we measured Th1/Th2/Th17 cytokines, both by flow cytometry. Furthermore IL-12 was measured by ELISA. Results. UT-POA did not alter DC or accessory molecules expression in BCII. However, H exhibited a decrease in the percentage of mDC (myeloid DC) and an increase in HLA-DR and CD86 expression at 1000 μg/mL. IL-12 secretion was modified only in the H group, increasing p70 subunit and decreasing p40 subunit. UT-POA increased Th1 (IFN-γ and IL-2), Th2 (IL-4) and Th17 (IL-17) secretion in both groups. Conclusions. UT-POA increased the production of cytokines related with anti-tumoral response at concentrations of 500-1000 μg/mL. This positive effect should be evaluated not only systemically but also in the tumor microenvironment in further studies. UT-POA may be a useful phytochemical in chemoprevention and in the alternative use in cancer therapies.