Nitrogen Fixation by symbiotic organisms is considered an important contribution to the solution of food problems throughout the world. For manyyears, Chinese scientists have focused their research in this area. Today more than half of the total nitrogen fertilizers applied are from biological fixation sources. The editor is an international renowned scientist at the Chinese Academy of sciences. He has brought together contributions from various research fields in China and Europe.Together they present the state-of-the-art in nitrogen-fixation research. The studies range from actino- mycete fixation induced in various genera andspecies of plants, mechanisms and chemical modeling of enzyme systems togenetical engineering of organisms.