α-Viniferin, an oligostilbene of trimeric resveratrol, has been reported to have antiinflammatory potential in carrageenin-induced paw edema or adjuvant-induced arthritis in animal models. However, little is known about the molecular basis. In this study, α-viniferin at 3 – 10 μM dose-dependently inhibited interferon (IFN)-γ–induced Ser⁷²⁷ phosphorylation of the signal transducer and activation of transcription-1 (STAT-1), a pivotal transcription factor controlling IFN-γ–targeted genes, in RAW 264.7 macrophages, and also IFN-γ–induced activation of the extracellular signal-regulated kinase (ERK)-1, a protein kinase upstream of the Ser⁷²⁷ phosphorylation of STAT-1. However, α-viniferin, only at a higher concentration of 10 μM, inhibited Janus kinase 2–mediated Tyr⁷⁰¹ phosphorylation of STAT-1 in the cells. To understand STAT-1–dependent inflammatory responses, we quantified nitric oxide (NO) or chemokines. α-Viniferin at 3 – 10 μM dose-dependently inhibited IFN-γ–induced production of NO, IFN-γ–inducible protein-10 (IP-10), or the monokine induced by IFN-γ (MIG) in RAW 264.7 cells and also that of NO in primary macrophages-derived from C57BL/6 mice. Furthermore, α-viniferin diminished IFN-γ–induced protein levels of inducible NO synthase (iNOS), attenuated mRNA levels of iNOS, IP-10, or MIG as well as inhibited promoter activity of the iNOS gene. In conclusion, this study proposes an antiinflammatory mechanism of α-viniferin, down-regulating STAT-1–inducible inflammatory genes via inhibiting ERK-mediated STAT-1 activation in IFN-γ–stimulated macrophages.