The objective of this study is to compare the long-term outcomes of infliximab therapy with lower-dose methotrexate (MTX; < or = 4 mg per week) and with standard-dose MTX (> or = 6 mg per week) in Japanese rheumatoid arthritis (RA) patients. One hundred thirty-eight patients with refractory RA were treated with intravenous infliximab; 106 patients underwent lower-dose MTX therapy, and 32 patients underwent standard-dose MTX therapy. Treatment responses at 54 weeks or last observation carried forward (LOCF) assessed using the European League Against Rheumatism (EULAR) response criteria were compared between the two groups. Eighty-eight patients (81.1%) in the lower-dose MTX group and 27 patients (84.3%) in the standard-dose MTX therapy completed 54 weeks of infliximab treatment. A EULAR response criteria good and moderate response was seen in 70.9% in the lower-dose group and 74.1% in the standard-dose group. Good and moderate treatment responses at 54 weeks or LOCF were seen in 66.0% in the lower-dose group and 68.7% in the standard-dose group. The outcome in the lower-dose MTX group was not significantly different from that in the standard-dose group. Therapy with MTX and infliximab was effective in Japanese RA patients, regardless of MTX dosage.