Abstract: Objective To study the effect of exogenous cytokine-stimulated decidual cells on IgG secretion of B lymphocytes and investigate the features of local immunological microenvironment of the decidua. Methods Exogenous cytokines interferon-γ (IFN-γ), interleukin-2 (IL-2), IL-6 and epidermal growth factor (EGF) were added separately in cultured decidual cells, and the supernatant of the culture medium was prepared for stimulating human peripheral blood lymphocytes. IgG secretion of the B cells was measured by radio-immunological method. Result The decidual cells of normal early pregnancy stimulated B lymphocyte IgG secretion, and the supernatant of exogenous cytokine-stimulated decidual cells had the same effect, which, however, was depended not on the concentration and category of the cytokines, but only on the time of treatment. Conclusion The exogenous cytokines can increase the humoral immunit in the decidual immunological microenvironment, but such effect might result from a self-regulatory mechanism of the local immunological microenvironment of the decidua, which can be fundamental for maintenance of normal pregnancy.