The efficacy and safety of a new tumor necrosis factor inhibitor, certolizumab pegol, in active rheumatoid arthritis has now been assessed in three phase III, multicenter, randomized, double-blind, placebo-controlled clinical trials. This commentary focuses on the paper by Keystone et al., in which patients were followed for the longest duration. This study, which compared two doses of subcutaneous certolizumab pegol with placebo in patients with active RA receiving methotrexate, showed no advantage of 400 mg over 200 mg certolizumab pegol over 52 weeks, after induction with 400 mg. The nature of the patients enrolled in this study, trial design and possible safety issues are discussed, as is whether this trial can teach us anything about tumor necrosis factor inhibitors in general. On the basis of the results from this study, certolizumab pegol does not represent a major addition to our armamentarium, but because of the slightly different mechanism of action and structure of this drug, and the apparently acceptable therapeutic effects over one year, it is, nevertheless, welcome.