In this study, we have concurrently assayed for IL-2, IL-4, IL-6, IL-10, TNF-alpha, and IFN-gamma in 24-h serum-free cultures of peripheral blood mononuclear cells (PBMC) obtained from seventeen patients with prostate cancer (CaP) per cytokine bead array analysis. The purpose of the study is to examine the nature of the cytokine profile operating among patients and to correlate with their physical, biochemical, and clinical parameters. Unstimulated PBMC cultures from patients with hormone-sensitive metastatic disease demonstrated elevated level of baseline TNF-alpha compared to patients with high-risk, locally advanced disease. Younger patients exhibited significantly higher levels of IL-4 and TNF-alpha compared to older patients following PHA stimulation. Similarly, significantly higher ratios of IFN-gamma/IL-4, IFN-gamma/IL-10, and IL-2/IL-4, a favorable type-1 cytokine pattern, were observed in patients with lower serum PSA compared to patients with high serum PSA. These results indicate the existence of distinct cytokine patterns among patients with CaP.