Biologics, both monoclonal antibodies (mAbs) and fusion proteins, have revolutionized the practice of medicine. This year marks the 30th anniversary of the Food and Drug Administration approval of the first mAb for human use. In this review, we examine the biotechnological breakthroughs that spurred the explosive development of the biopharmaceutical mAb industry, as well as how critical lessons learned about human immunology informed the development of improved biologics. We also discuss the most common mechanisms of action of currently approved biologics and the indications for which they have been approved to date. (C) 2016 Elsevier Inc. All rights reserved.