Abstract Background: In certain pathophysiological conditions, such as inflammation rheumatoid arthritis and diabetes mellitus (DM), alterations in asparagine-linked glycan ( N-glycan) patterns of the acute-phase protein, α 1-acid glycoprotein (AGP), have been reported. In this study, we investigated N-glycan structures of AGP purified from the sera of patients with acute inflammation ( n=5), type 2 diabetes mellitus ( n=5), and healthy individuals ( n=5). Methods: N-Glycans were released with peptide N-glycosidase F (PNGase F) from denatured AGP and purified with cellulose cartridge. N-glycans were analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS) in combination with exoglycosidase digestion. Results: We revealed increases in bi-antennary complex glycans and in α1–3 fucosylated bi-, tri-, and tetra-antennary glycans and a decrease in tri-antennary glycans in inflammation patients. These results support increases in bindings to concanavalin A (ConA) and Aleuria aurantia lectins (AALs). In diabetic patients, the pathogenesis-specific change in N-glycan patterns of AGP was not significant. Conclusions: The MALDI-TOFMS method is sensitive and suitable for profiling analysis of N-glycans in clinical samples.