Blood microsampling techniques, such as dried blood spot (DBS), capillary microsampling and microdialysis, offer many advantages compared with traditional liquid blood or plasma sampling. The nine chapters of this book present the state of the art for the various microsampling techniques currently available, along with the analytical techniques and challenges associated with them. The whole process is considered, from sample collection in the clinic, to bioanalysis and then interpretation of data from microsamples by the end user (pharmacokineticists, toxicologists and clinicians), together with current regulatory implications. The book also includes case studies where these techniques have been used successfully with the understanding that no innovation is without its honorable failures. Finally, the book addresses future developments, both technical and general, and how these technologies will continue to grow and find applications.