Otelixizumab is a humanized, aglycosyl, non-mitogenic, anti CD3 monoclonal antibody (MAb) directed against the ε domain of the human lymphocyte antigen CD3, which is currently undergoing phase III clinical trials in adult new-onset type I diabetes mellitus patients and has been evaluated in rheumatoid arthritis and psoriasis patients in small exploratory studies. Otelixizumab has been administered via the subcutaneous route as a single dose in type I diabetes patients. This study is a randomised, single-blind, placebo-controlled, repeat dose study of otelixizumab administered subcutaneously in rheumatoid arthritis patients. One cohort will receive a single dose of adalimumab (HUMIRA, Abbott) as rescue medication to assess additional concomitant safety and tolerability issues.