This book constitutes the refereed proceedings of the 8th East European Conference on Advances in Databases and Information Systems, ADBIS 2004, held in Budapest, Hungary, in September 2004.The 27 revised full papers presented together with an invited paper were carefully reviewed and selected from 130 submissions. The papers are organized in topical sections on constraint databases, deductive databases, heterogenous and Web information systems, cross enterprise information systems, knowledge discovery, database modeling, XML and semistructured databases, physical database design and query evaluation, transaction management and workflow systems, query processing and data streams, spatial databases, and agents and mobile systems.