Despite the progress in human medicine, some viral diseases are the leading causes of death in humans worldwide. The lack of effective therapies and the quick emergence of new drug-resistant viruses have urged a need for developing new agents to treat viral diseases. Several hundred natural products have been isolated for screening and identifying antiviral activity, and some have been shown to have great medicinal value in preventing and/or ameliorating viral diseases in preclinical and clinical trials. There are innumerable potentially useful medicinal plants and herbs waiting to be evaluated and exploited for therapeutic applications against genetically and functionally diverse virus families. This book focuses on several pathogenic viruses and antiviral natural compounds. we tried to use an update literature to most viral disease and understandable materials for public individuals. It can also provide clues for further research to researchers. The authors of this book have reviewed more than 300 articles and books.