Lower adiponectin levels in circulation are shown to be associated with endothelial dysfunction, which is a crucial feature in the evolution of atherosclerosis. The aim of our study is to evaluate the effect of anti-tumor necrosis factor (TNF) therapy on adiponectin levels with endothelial function and arterial stiffness. Fifteen Japanese patients with rheumatoid arthritis (RA) received infusions with infliximab (3 mg/kg) at weeks 0, 2, and 6. Serum concentrations of adiponectin, endothelial function, and pulse wave velocity (PWV) were measured before each infusion. Endothelium-dependent vasodilatation and endothelium-independent vasodilatation were evaluated as forearm blood flow response to reactive and nitroglycerin-induced hyperemia using strain-gauge plethysmography. Endothelium-dependent vasodilatation was significantly improved at 2 weeks and 6 weeks by treatment with infliximab. PWV remained unchanged. Anti-TNF therapy significantly increased serum adiponectin levels at 2 weeks and 6 weeks. The adiponectin levels were positively correlated with the endothelium-dependent vasodilatation, and negatively with the disease activity score of 28 joints. Our study shows a short-term efficacy of infliximab on adiponectin levels and endothelial dysfunction of patients with RA, and provides additional evidence to support the regulatory role of TNF-alpha on the expression of adiponectin in vivo.