We investigated the effects of anti-IL-6 receptor antibody, tocilizumab (TCZ), on lipid metabolism. Nineteen patients with rheumatoid arthritis (RA), entered in clinical case-control study of SAMURAI trial at Sasebo Chuo Hospital, were examined. Nine patients received TCZ monotherapy at 8 mg/kg intravenously every 4 weeks (TCZ group) and 10 patients received conventional DMARDs (control group). Serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), apolipoprotein (Apo) A-1, Apo A-2 and Apo B as well as disease activity score (DAS), C-reactive protein and serum amyloid A protein were examined at baseline and after 3 months of the treatment. IL-6 inversely was correlated with LDL, Apo A-1 and Apo A-2, and also tended to correlate with Apo B. In TCZ group, serum levels of TC, HDL, LDL, Apo A-1 and Apo A-2 were significantly increased after 3 months treatment with TCZ. There was no significant change in Apo B, the atherogenic index, and TC/HDL by the TCZ treatment. Changes in the DAS28-ESR negatively correlated with those in TC. In one patient, whose serum level of TCZ was not detected after 3 months of the treatment, the absence of the increment in serum levels of Apo A-1 and A-2 in the patient was remarkable. All of the markers did not change during 3 months in control group. These data may raise an important issue to evaluate the impact of these alternations in lipid metabolism for longer periods in RA patients treated with TCZ.