Rituximab has recently been reported in retrospective studies to be effective in pemphigus at the dosing schedule used for treating rheumatoid arthritis (RA) of two 1,000 mg infusions 2 weeks apart. While the effect of rituximab on B cells has been well described, its effect on global T cell function has not been assessed. Ten patients who received RA dosage rituximab were prospectively assessed for clinical response. Immunological response including autoantibody titers, CD20+ B cell, and CD4+ T cell counts was assessed pre- and post-treatment. The CD4+ T cell function was determined by a novel assay measuring intracellular ATP levels in response to mitogenic stimulus. At 6 months, 90 % of patients achieved remission. Disease control and remission were achieved at median times of 1 and 3.7 months, respectively. There was a 67 % relapse rate during an average follow-up of 22 months. Global CD4+ T cell numbers and function were preserved 3 months after rituximab. A single cycle of RA dosage rituximab with concomitant immunosuppression is effective in pemphigus. We did not find an effect on total CD4+ T cell numbers or function 3 months after treatment.