Within the growing field of proteomics, mass spectrometry is now established as a powerful tool for peptide and protein identification and discovery from purified samples. A new era is now beginning, with the development of MALDI imaging, maintaining the sensitivity and efficacy of both discovery and identification while additionally preserving the anatomical integrity of biomolecules like peptides, proteins, oligonucleotides and lipids within tissues. Crucial developments for sample preparations have made leaps and bounds, as it is now possible to work with freezed conserved biopsies (- 80 degrees c) of more than 6 months or even conserved after paraformaldehyde fixation and paraffin embedding. The latter development has opened the door to archived tissues in hospital libraries and biomarkers hunting from tissues derived from these libraries are now a key objective. The relationship between MALDI imaging and immunocytochemistry used by the pathologist is important. The development of specific MALDI imaging using probes with a tag (peptide or organic) called << Tag-Mass >> adds a whole new perspective. It is possible henceforth to localize a protein with its specific mRNA and more specifically, with its signalling pathway on the same sections or within a pathology expression phenotype from a biopsy. Development of such a technology is similar to the one that occurred several years ago for nuclear magnetic resonance (NMR) that leads the development of imaging technologies called MRI in hospital which is intensively used for pathology diagnostics.