This book constitutes the refereed proceedings of the Third East European Conference on Advances in Databases and Information Systems, ADBIS'99, held in Maribor, Slovenia in September 1999. The 26 revised full papers presented together with two invited papers were carefully reviewed and selected from a total of 94 submissions. The papers are organized in topical sections on information retrieval and multimedia, integration, transactions, index structures, agent technology, data mining, data modeling, incomplete data, queries, database theory, and performance issues.