Biological mass spectrometry (MS) is an important analytical approach to assess the mass of biomolecules with high accuracy, sensitivity and speed of analysis. It has wide applications and it is of fundamental importance to answer many diverse biological questions. In my thesis I briefly introduce the four types of biological MS I used during my scientific career. I illustrate my work during my PhD studies (2001-2005) and as postdoctoral fellow (2006-2011) working in England and in Switzerland. Finally, I describe my past, current and future MS investigations I carry out at the Institute of Structural Biology (IBS) in Grenoble. To conclude, MS represents an emerging tool in structural biology because it provides novel insights on the two dimensional map of macromolecular assemblies with high sensitivity, complementing traditional structural biology approaches.