After earlier meetings in Enschede (NL, 1994), Basel (CH, 1996) and Banff (CDN, 1998), muTAS 2000 is the fourth international symposium on the subject of miniaturized techniques, methods, devices and systems for (bio)chemical analysis and synthesis. Initially started as a minor sub-topic in the large field of Micro System Technology (MST or MEMS), the field of muTAS is currently generally considered as one of the most important application areas of MST, which is reflected in the still rapidly growing research, development, and, above all, commercialization activities. Apart from further development and refining of the research on electrophoretic separation, electrokinetically driven flow systems, cell manipulation and analysis, miniaturized flow systems and study of microfluidics, the important new area of centrifugal microfluidics on CD devices receives broad attention. On the other hand, new innovations range from topics as exotic as photoacoustic detection in microreactors and molecular emission detection on a chip to very high-pressure microreactor devices and shear-flow driven separations. The enormous speed of the developments in this field is illustrated by the large number of new start-up companies, some of them based upon technologies that were not even published at the former meeting in Banff in 1998. All this illustrates the great excitement that continues to govern this field in which generation and analysis of (bio)chemical information using microtechnology becomes more and more entangled in what one could call micro (bio)chemical systems. This volume contains the proceedings of the fourth international symposium on Micro Total Analysis Systems (muTAS 2000), held 14-18 May 2000, at the University of Twente in Enschede, The Netherlands, and organised by the MESA+ Research Institute. Cutting-edge research of all invited and contributed papers presented by the world's leading &mgr;TAS groups provide the neweststate of the art of this electrifying, multidisciplinary field.