This Application Note demonstrates the utility of capillary electrophoresis/mass spectrometry (CE/MS) for the analysis of intact monoclonal antibodies (mAbs). The Agilent 7100 CE System coupled to an Agilent 6530 Q-TOF LC/MS was used to study the intact and reduced forms of mAbs. The combination of mass measurements obtained by CE/MS and the data processing capabilities of Agilent MassHunter and BioConfi rm Software enables the identifi cation of heterogeneity in an intact mAb and its fragments. The result demonstrates the utility of CE/MS as a complementary technique to liquid chromatography/mass spectrometry (LC/MS) for the analysis of mAbs.