Book excerpt: Very fast advances in IC technologies have brought new challenges into the physical design of integrated systems. The emphasis on system performance, in lately developed applications, requires timing and power constraints to be considered at each stage of physical design. The size of ICs is decreasing continuously, and the density of power dissipated in the circuits is growing rapidly. The first challenge is the Information Technology where new materials, devices, telecommunication and multimedia facilities are developed. The second one is the Biomedical Science and Biotechnology. The utilisation of bloodless surgery is possible now because of wide micro-sensors and micro-actuators application. Nowadays, the modern micro systems can be implanted directly into the human body and the medicine can be applied right in the proper time and place in the patient body. The low-power devices are being developed particularly for medical and space applications. This has created for designers in all scientific domains new possibilities which must be handed down to the future generations of designers. In this spirit, we organised the Fourth International Workshop "MIXED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS" in order to provide an international forum for discussion and the exchange of information on education, teaching experiences, training and technology transfer in the area of microelectronics and microsystems.