Background/Aims: The androgen dehydroepiandrosterone (DHEA) attenuates allergic inflammatory airway reactions by down-regulating the Th2 response in mice. The purpose of this study was to investigate whether DHEA suppresses Th2 cytokine production in cultured peripheral blood mononuclear cells (PBMCs) from asthmatic patients. Methods: Sixty-one consecutive suspected asthmatic or non-asthmatic men underwent tests for asthma. PBMCs from each subject were cultured with and without DHEA (0.01～10 μM) for 48 h. The concentrations of interferon (IFN)-γ, interleukin (IL)-5, and IL-10 in the culture supernatant were measured via an enzyme-linked immunosorbent assay. Results: In PBMCs from subjects exhibiting methacholine airway hyperresponsiveness (AHR), DHEA significantly suppressed IL-10, IL-5, and IFN-γ production in a dose-dependent manner (all p<0.001) and tended to increase the IFN-γ/IL-5 ratio (p=0.087). DHEA (10 μM) suppressed cytokine production to a greater degree in subjects with