Swine can be infected with different mycoplasmas. Some of them are important pathogens, causing significant health and welfare issues in pigs and major losses to the swine industry worldwide. Other mycoplasmas are not pathogenic for swine and can be considered commensals. The present book provides up-to-date scientific, clinical and practical information of the most important pathogenic mycoplasmas in swine. Most emphasis has been placed on Mycoplasma hyopneumoniae, as this is economically the most important Mycoplasma sp. in swine. However, other pathogenic species like Mycoplasma hyorhinis, Mycoplasma hyosynoviae and Mycoplasma suis are discussed. Every chapter has been written by internationally renowned scientists and clinicians from all over the world; each with in depth knowledge, expertise and experience in the particular areas of swine mycoplasmas. In total, more than 40 persons have contributed as authors. Two independent reviewers and the editors have critically evaluated every chapter of the book, and original versions have been revised accordingly. This procedure should guarantee the evidence-based character of the book, the high scientific level and the practical relevance of the content. The book aims to serve the scientific and veterinary community and the swine industry worldwide. It may be relevant for scientists from universities, research institutes and diagnostic laboratories, persons involved in veterinary and animal science education, swine practitioners, and veterinarians and health professionals working in industry. We are grateful to all who have contributed to this book, to the companies that have supported the initiative to bring together all information related to swine Mycoplasma and helped with the distribution of the book, and last but not least to all colleagues who will read the book.