All eukaryotic cell surfaces are covered with a thick layer, called ‘Glycocalyx’, of complex carbohydrate molecules conjugated to proteins and lipids. The complex carbohydrates are also known as glycans. The entire repertoire of glycans present on the cells, tissues of an organism is called ‘Glycome’ and the study of structure and functions of glycome is referred to as Glycomics. Glycans are important for cell-cell communication, cell-matrix and cell-pathogen interactions and consequently, are involved in numerous functions including development, signaling, immune response, glycoprotein quality control, and disease progression, etc. The structures of N- and O-glycans are not only complex and diverse but also cell-type dependent. Thus, the structural elucidation of glycans remains a major challenge. Recent advancements in tandem mass spectrometric techniques like MALDI-TOF/TOF, in conjunction with glycolytic enzymes have made possible to obtain in-depth structural information about glycans. In this presentation, structural analysis of N- and O-glycans from resting and activated human neutrophils, and murine embryonic stem cells will be discussed. The data from these studies demonstrates that changes in the structure of glycans can be subtle or dramatic depending upon the cell-type and function.