Monoclonal antibodies (mAbs) represent a class of biotechnology-derived therapeutics for use in the treatment of various disease indications such as oncology, autoimmune, cardiovascular, and metabolic disorders. Monoclonal antibodies are immunoglobulin (Ig) proteins engineered to bind to specific antigens with high specificity. The concepts reviewed in this paper include 1) the regulatory procedures and guidelines that apply to mAbs, 2) the types of toxicology studies applicable to mAbs, and 3) the scientific challenges, such as the selection of a relevant animal species and the development of anti-drug antibodies, that can arise due to the unique properties of mAbs.