1. Denitrification: Appraisal and Concluding Remarks.- The Denitrifying Bacteria.- 2. Effects of Environmental Factors on Denitrification.- 3. Microbiology of Denitrification and other Processes Involving the Reduction of Oxygenated Nitrogenous Compounds.- 4. Diversity of Denitrifiers and their Enzymes.- 5. Genetics of Denitrification in Pseudomonas Aeruginosa and Stutzeri.- 6. Current Methods used to estimate N2O and N2 Emissions from Field Soils.- 7. Influence of pH and Partial Oxygen Pressure on the N2O-N to N2 Ratio of Denitrification.- 8. Denitrification Loss from Managed Grassland.- Denitrification in Agriculture.- 9. N2O-Formation during Soil Cropping.- 10. Nitrate Reduction in the Subsoil.- 11. Preliminary Field Denitrification Studies of Nitratefertilized and Nitrogen-fixing Crops.- Denitrification in Aquatic Environments.- 12. Significance of Denitrification on the Strategy for Preserving Lakes and Coastal Areas against Eutrophication.- 13. Marine Denitrification.- 14. Denitrification in Freshwaters.- 15. Application of Denitrification in the Wastewater Treatment.- 16. Denitrification by Methanotrophic/Methylotrophic Bacterial Associations in Aquatic Environments.- 17. Simultaneous Nitrification and Denitrification in Lake Erken Sediments.