This publication is the proceedings of the sixth international symposium on naturally occurring radioactive material (NORM), which was organized in cooperation with the IAEA as part of its programme to promote application of the safety standards to natural sources of radiation and to disseminate information to Member States. NORM VI provided an opportunity to review the many developments that had taken place over the past three years since the previous symposium in this series. NORM VI was attended by 140 participants from 33 countries. The proceedings contain all 38 oral presentations and four rapporteur reports, as well as a summary that concludes with the main findings of the symposium. Text versions of 43 poster presentations are provided on the attached CD-ROM.