MALDI MS imaging mass spectrometry can be used to map the distribution of targeted compounds in tissue sections with a spatial resolution currently of about 50 microm, providing important molecular information in many areas of biological research. After matrix application, a raster of a section by the laser beam yields ions from compounds in a tissue mass-to-charge range from 1000 to over 100000. Two-dimensional intensity maps can then be reconstructed to provide specific molecular images of a tissue.