Head-to-head studies as randomized, double blind clinical studies are the best method for directly comparing the efficacy of different therapeutic strategies. However, at the moment no such studies are available for biological agents in the treatment of patients with rheumatoid arthritis. Therefore it is only possible to compare different treatment strategies by indirect comparisons, for example by adjusted indirect comparison or mixed treatment comparison (MTC). The MTC is accepted by European authorities as supportive clinical evidence. As with the case of meta-analyses the quality of an indirect comparison is determined by the homogeneity of the studies included in the analysis.A short review of eight published indirect comparisons of the efficacy of biological agents in the treatment of patients with rheumatoid arthritis showed that the results with respect to tumor necrosis factor (TNF) blockers are similar and that there are differences in the efficacy of non-TNF biological agents.