By binding to the androgen receptor (AR), androgen mediates an array of physiological proces-ses. There are two kinds of AR, intracellular AR and membrane AR. Intracellular AR belongs to the family of nuclear receptor and contains three domains, i.e. transactivation domain, DNA binding domain and lig-and binding domain. Membrane AR is a newly identified class of AR that can cause a rapid rise of intracellu-lar Ca2+ concentration and the subsequent downstream signal transductions. Recent research shows that an-drogen and AR play an important role in the development and reactivity of the immune system.