The production of cytokine is a key event in the initiation and regulation of an immune response. Many compounds are now used routinely to modulate cytokine production, and therefore the immune response, in a wide range of diseases, such as cancer. Interleukin-2 and tumor necrosis factor-alpha are two important cytokines in antitumor immunity. In this study, the effects of Lycium barbarum polysaccharide-protein complex (LBP(3p)) on the expression of interleukin-2 and tumor necrosis factor-alpha in human peripheral blood mononuclear cells were investigated by reverse transcription polymerase chain reaction (RT-PCR) and bioassay. Administration of LBP(3p) increased the expression of interleukin-2 and tumor necrosis factor-alpha at both mRNA and protein levels in a dose-dependent manner. The results suggest that LBP(3p) may induce immune responses and possess potential therapeutic efficacy in cancer.