The past decade has seen the growth of analytic methodologies based on antibody and DNA probe technologies. In fact, these two technologies have revolutionized the whole field of human, veterinary, and agriculture diagnostics. The emphasis has been to develop tests that are fast, reliable, and user-friendly, and that can be performed on site by attending individuals or patients. The tests should also be amenable to automation for high throughput for use in commercial and hospital laboratories. The mushroomed growth of such diagnostics has created a niche for a book that can bring together the perspective of the upcoming technologies that are otherwise in their infancy. The intent of this book is to present readers with these state-of-the-art futuristic methods, which will be the hallmark of diagnostics in the twenty-first century. These new technologies have lain the foundation for a plethora of new diagnostic companies whose products are still not fully accepted because of practical challenges and the newness of their ideas. The chapters in this book have been written by world-renowned authorities in their fields of expertise. All aspects of diagnostics are covered: clinical, agriculture, veterinary, and environmental. State-of-the-art immunodiagnostic methods such as nephelometric immunoassay, time-resolved fluoroimmunoassay, and threshold immunoassay are discussed. Chapters on DNA-probe-based diagnostics and PCR technology are also included, since they are finding their ways rapidly because of their specificity and ease of probe production. A chapter on biosensors discusses the latest development on this topic and its possible potential in modem-day diagnostics.