CD4+CD25+regulatory T cells (Tregs) play a key role in regulation of immnue response and maintenance ofself-tolerance. Studies have found Tregs could suppress tumor-specific T cell-mediated immune response andpromote cancer progression. Depletion of Tregs can enhance antitumor immunity. Dendritic cells (DCs) areprofessional antigen-presenting cells and capable of activating antigen-specific immune responses, which makethem ideal candidate for cancer immunotherapy. Now various DC vaccines are considered as effective treatmentfor cancers. The aim of this study was to evaluate variation of Tregs in BALB/C mice with hepatocellular carcinomaand investigate the interaction between tumor-derived Tregs, effector T cells (Teff) and splenic DCs. We foundthe percentages of Tregs/CD4+ in the peripheral blood of tumor-bearing mice were higher than in normal mice.Tumor-derived Tregs diminished the up-regulation of costimulatory molecule expression on splenic DCs, evenin the presence of Teff cells and simultaneously inhibited IL-12 and TNF-α secretion by DCs.