Chronic infection and resulting inflammation promote tumor development and progression, and Toll-like receptors (TLRs) may play an important role in this process. The aim of this study was to determine whether CpG oligonucleotides (CpG-ODN), which are Toll-like receptor 9 (TLR9) agonists, can promote inflammatory cytokines release from the prostate cancer PC-3 cells through activation of nuclear factor-kappaB (NF-kappaB). Flow cytometry, semiquantitative real-time reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, and immunofluorescence analysis were used to detect the transforming growth factor-beta1 (TGF-beta1) and interleukin-8 (IL-8) release and NF-kappaB activation in PC-3 cells after CpG-ODN stimulation. CpG-ODN promoted the expression and secretion of immunosuppressive cytokines TGF-beta1 and IL-8 from PC-3 cells. In addition, after CpG-ODN stimulation, NF-kappaB nuclear translocation was also observed in PC-3 cells, contributing to CpG-induced upregulation of IL-8 and TGF-beta1. Thus, TLR9 agonists may promote IL-8 and TGF-beta1 production in human prostate cancer cells through NF-kappaB activation.