This book, in its third edition, has been completely revised giving latest information on poultry diseases including avian influenza. The basic syllabus pattern of Veterinary Council of India has been retained for students. Information on drugs, disinfectants, sanitisers and vaccines has been almost rewritten. Chapters on Laboratory Procedures has been revised and enlarged. Important chapters such as on Fungal Toxicosis, Marck`s Disease, Gumboro Disease, Coccidiosis Poultry Immune System, have been updated. Diseases of ducks have been included related to the expansion of duck rearing. A chapter on quality of drinking water and problems of egg shell have been added.The book retains its original approach of providing theoretical information, diagnosis methods for accurate diagnosis, treatment by latest drugs available in India and lastly prevention of diseases by latest vaccines.