Electron probe X-ray microanalysis can be used to determine the elemental composition of cells and tissues in defined functional states. However, reliable quantitative data can be expected only after appropriate cryopreparation techniques. The most versatile preparation and analysis technique can be outlined by four succeeding steps: 1. Cryofixation, 2. Cryoultramicrotomy, 3. Cryotransfer including freeze-drying, 4. Energy dispersive X-ray microanalysis.