The explosion in the late 20th century of the field of analytical chemistry, and particularly for biological purposes has led to a need for fast, integrated, portable, more reliable and more sensitive tools that could handle reduced amount of samples. Microfluidics and lab-on-a-chip devices provide a good answer to this quest to miniaturized and enhanced analysis and they lend themselves well to mass spectrometric detection as similar amounts of samples, in the low microliter range, are handled on a chip and required for a single MS analysis. "Miniaturization and Mass Spectrometry" illustrates this trend and focuses on one particular analysis technique, mass spectrometry whose popularity has 'dramatically' increased in the last two decades with the explosion of the field of biological analysis and the development of two 'soft' ionization techniques, ESI and MALDI which enable the analysis of large but fragile molecules, such as biological molecules (DNA, proteins, oligosaccharides...).