The start of the new year signals that it is time for mAbs' annual review of the therapeutic monoclonal antibodies (mAbs) in active Phase 2/3 or Phase 3 clinical studies. The entire clinical pipeline currently includes ~350 mAbs, but most of these are in early development. As of the beginning of 2013, our "Antibodies to watch" list includes 28 single mAbs and one mAb mixture that are undergoing evaluation in Phase 3 studies for inflammatory or immunological disorders, cancers, high cholesterol, osteoporosis, Alzheimer disease and infectious disease. In alphabetical order, the 28 mabs are alirocumab, AMG 145, elotuzumab, epratuzumab, farletuzumab, gantenerumab, gevokizumab, inotuzumab ozogamicin, itolizumab, ixekizumab, lebrikizumab, mepolizumab, naptumomab estafenatox, necitumumab, nivolumab, obinutuzumab, ocrelizumab, onartuzumab, racotumomab, ramucirumab, reslizumab, romosozumab, sarilumab, secukinumab, sirukumab, solanezumab, tabalumab, and vedolizumab. The mixture of actoxumab and bezlotoxumab is being evaluated in two Phase 3 studies as a treatment for Clostridium difficile infection.