Protein glycosylation is a highly complex and regulated posttranslational modification. In this process several glycosyltransferase families are involved. In cancer this delicate equilibrium is disrupted leading to glycosylation changes on glycoconjugates, namely, glycoproteins. One of the major consequences is the increase of sialylated oligosaccharide chains in glycoproteins. Here we describe an experimental methodology focused in the enrichment and characterization of sialic acid containing glycopeptides by MALDI mass spectrometry and the subsequent data analysis.