This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Decorin N-glycans are not well characterized. Although numerous structural studies have been done on decorin, these have been mostly focused on the core protein and the glycosaminoglycan chain. The biological roles of decorin especially the roles of post-translational modifications are understood better as the structure of decorin proteoglycan is elucidated. The purpose of this paper is to establish the N-glycosylation patterns of the normal decorin. A survey of the N-linked glycans released from the core protein using PNGaseF was determined using MALDI-TOFMS. The spectral profile showed [M+Na]+ ions that correspond to high mannose type structures and complex/hybrid structures that contain fucose and sialic acid. To further characterize the identified glycans, tandem MS analysis of the permethylated [M+2Na]2+ ions was performed using ESIMS and LCMS. The tandem mass spectra of the high mannose type structures show fragmentation patterns consistent with well known Man5-7GlcNAc2 structures. Several complex and hybrid glycan ions were identified and the product ion profile of the [M+2Na]2+ ions were consistent with the presence of conventional unsubstituted and fucosylated cores as well as fucosylated antennae. Decorin articular cartilage tissues exhibit an unusual biantennary configuration where both branches terminate with a HexNAc-HexNAc that is fucosylated and sialylated.