[A powerful tool for study of sperm--soft X-ray microscopy]. 
Soft X-ray microscopy is a microimaging technique using soft X-ray as illuminative source.  It fills the gap between optical and electron microscopy.  Soft X-ray microscopes have better resolution than visible microscopes.  In comparison with electron microscopes, it can examine thick (up to 10 micrometers for biological samples) and wet specimens in their natural states without being dehydrated, sectioned and stained.  In addition, soft X-ray microscopy can map elements and analyze the biological macromolecules such as protein and DNA in the examined samples.  In this paper, the advantages of soft X-ray microscopy for biology are briefly described.  The applications of soft X-ray microscopy to the analysis of mammal and human sperm are illustrated.