The Opuntia ficus-indica extract(OFE) has been claimed to have several therapeutic properties including anti-inflammation and anti-rheumatoid arthritis in oriental medicine but little is known about their effect on macrophages. This study demonstrated that OFE could stimulate TNF-alpha production in cultured macrophages. which is one of important mediators in autoimmune diseases including experimental autoimmune encephalomyelitis(EAE). In vivo study showed that oral administration of OFE exacerbate the onset of clinical paralysis. This finding suggests that OFE stimulates cytokine production and exacerbates autoimmune inflammatory diseases including EAE.