Recent technological innovations - influenced primarily by the development of more sophisticated, faster and cheaper computer systems - have permitted the evolution of more affordable systems for Patient Data Management (PDMs). The experience of the authors, on one of the first PDMs installation sites in Europe, shows that the purchase of such a system is not an easy task. Therefore, the first part of the book is devoted to a comparison of already installed, commercially distributed PDMs with regard to their specifications, functions and performance. Different systems (which are all in clinical use) were checked for the availability and ease of use of their functions. In the second part of the text, different vendors whose systems were included in the study describe the systems from their viewpoints. The text concludes by showing how to use PDMs data for scientific and therapeutic purposes.