Advanced Computer Systems is a collection of forty selected papers presented to the Eighth International Conference on Computer Systems, October 2001 in Mielno, Poland. These papers provide a comprehensive summary of practice and research progress in information technologies: • Recognition, Security and Safety concentrates on the widely-known problems of information systems security. • Methods of Artificial Intelligence presents methods and algorithms which are the basics for the applications of artificial intelligence environments. • Intelligent Agents and Distributed Activities includes laboratory research on multiagent intelligent systems as well as upon their applications in searching information, negotiating and supporting decision. • Distributed Productions Networks and Modeling Complex Systems present production processes in distributed shared virtual environment, virtual solution of integer optimization problems, and a queuing approach to performance optimization in the distributed production network.