The series, "Hungarian Conference and Exhibition on Materials Science, Testing and Informatics", was founded in order to provide a forum in which Hungarian and foreign scientists and research groups - interested in metals and alloys, silicates, polymers and composites - would have the opportunity to exchange and publish ideas and to establish new integrated partnerships. The 4th Hungarian Conference and Exhibition on Materials Science, Testing and Informatics was held on the Balaton lakeside, at Balatonfüred, October 12-14th, 2003. The following topics are covered in the proceedings: functional materials and technologies of the new millennium (including mechanical engineering, electrotechnics, energetics, ceramics, polymers, biotechnology, nanostructures, smart materials, gradient materials); modern research and characterization methods; modeling, simulation and materials informatics; innovative products and technologies. The proceedings are therefore an invaluable source of up-to-date information on the field.