The third edition of Textbook of Microbiology has been thoroughly updated to include the latest developments including pathogenesis, laboratory diagnosis and treatment. Brief description of avian influenza virus and severe acute respiratory syndrome has been given in chapters on Orthomyxoviridae and Caliciviridae respectively. In the chapter on hospital-associated infections, antibiotic policy and disinfection policy have been added. The text is presented in a simple and lucid manner. All figures are now computer-drawn and in different colours which makes the book colourful and the reader can have a better understanding. Key facts at the end of each chapter are another addition. These are very useful for a quick revision and recapitulation by the students. 1 general bacteriology. 2 systemic bacteriology. 3 virology. 4 medical mycology. 5 clinical microbiology. 6 bacteriology of water, milk and air, and biological warfare.