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.