Phellinus linteus (PL), one of the immune-regulatory substances, is recognized to play the role in the metabolic process on inflammation and immunity. It has been traditionally used in the oriental medicine to treat inflammatory related disease. The purpose of this study was to evaluate the effects of water extracts of PL on the mesenteric lymph node lymphocytes immune function in the ICR male mice. Control mice received vehicle only. The PL treated mice were administered the respective extract by oral gavages for 4 weeks. IgE concentrations in serum and MLN lymphocytes were significantly lower in PL treated mice than in control mice. PL increased the proportion of CD4+ and CD8+ T cells in MLN lymphocytes. PL significantly decreased Th2 cytokine concentrations and mRNA expression levels in cytokine secretions. Therefore, water extracts of PL modulate inflammatory parameters through regulation of immunoglobulin production resulting from decreased Th2 cytokine secretion and mRNA expression levels and reduce pro-inflammatory cytokine secretion and mRNA expression in MLN lymphocytes.