Bispecific antibodies are antibodies that simultaneously recognize two antigens. This characteristic allows for bridging between two cells and simultaneous recognition of two antigens on target cells, leading to improvements in functions and specificity that could not be achieved with conventional antibodies. As of December 2023, 11 types of bispecific antibodies have been approved by the US Food and Drug Administration (FDA), eight of which are T cell-engaging bispecific antibodies (Fig. 112.1). The formats of bispecific antibodies are broadly divided into fragment antibodies that do not have a fragment crystallizable region (Fc) sequence or IgG type antibodies (those using antibody engineering techniques such as Knobs-into-holes, DuoBody, CrossMab, etc.) [1]. The glycan structures of bispecific antibodies (IgG type), like that of conventional therapeutic antibodies, influence their functionality, safety, and pharmacokinetics. Therefore, analyzing their glycan structures and heterogeneity is essential for the production, process optimization, and quality control of bispecific antibodies.