The effect of human pregnancy-specific glycoprotein (PSG) on the cytokine and chemokine production in vitro by intact mononuclear cells was studied by the method of flow fluorimetry. PSG inhibited production of the proinflammatory cytokines IL-6, IL-8, IL-17, IFN-γ, and TNF-α and chemokines CCL3/MIP-1α, CCL4/MIP-1β, CCL2/MCP-1; at the same time, PSG stimulated IL-12(p70) production. Simultaneously with increasing the VEGF level, PSG inhibited production of IL-9, IL-13, G-CSF, and GM-CSF. The PSG effect discovered can be interpreted as a contribution into the immune tolerance formation during pregnancy