Purpose: Glycosylation of acute-phase proteins (APP), which is partially regulated by cytokines, may be distinct in disease and provide useful tumour markers. Thus, we have examined the glycosylation of major serum APP in pancreatic cancer (PaC), chronic pancreatitis (CP) and control patients.Experimental design: Using a specific anti-sialyl Lewis X antibody and N-glycan sequencing, we have determined glycosylation changes on alpha-1-acid glycoprotein (AGP), haptoglobin (HPT), fetuin (FET), alpha-1-antitrypsin (AT) and transferrin (TRF).Results: Increased levels of sialyl Lewis X (SLe(x)) were detected on AGP in advanced PaC and CP and on HPT, FET, AT and TRF in CP. An increase in N-glycan branching was detected on AGP and HPT in the advanced stage of PaC and CP and on FET and TRF in the CP. A core fucosylated structure was increased on AGP and HPT only in the advanced PaC patients.Conclusions and clinical relevance: Changes in APP SLe(x) and branching are probably associated with an inflammatory response because they were detected in both advanced PaC and CP patients and these conditions give rise to inflammation. On the contrary, the increase in APP core fucosylation could be cancer associated and the presence of this glycoform may give an advantage to the tumour.