The number of therapeutic monoclonal antibodies (mAbs) continues to increase. In order to reduce sound-alikes and specify structural components of the immunoglobulins, the World Health Organization International Nonproprietary Names (INN) Programme has developed four new suffixes to be used instead of “mab” for antibodies developed from 2022 onward. Unmodified immunoglobulins will end in “tug”; mAbs with an engineered constant region will end in “bart”; bifunctional mAbs will end in “mig”; and variable region fragments will end in “ment.”