Heparin and heparan sulfate (HS) are important pharmaceutical targets because they bind a large number of proteins, including growth factors and cytokines, mediating many biological processes. Because of their biological significance and complexity, there is a need for development of rapid and sensitive analytical techniques for the characterization and compositional analysis of heparin and HS at the disaccharide level, as well as for the structure elucidation of larger glycosaminoglycan (GAG) sequences important for protein binding. In this work, we present a rapid method for analysis of disaccharide composition using reversed-phase ion-pairing ultraperformance liquid chromatography coupled with electrospray time-of-flight mass spectrometry ((RPIP)-UPLC-MS). Heparin disaccharide standards were eluted in less than 5 min. The method was used to determine the constituents of GAGs from unfractionated heparin/HS from various bovine and porcine tissues, and the results were compared with literature values.