The Commission for the Hydrology of the Rhine basin (CHR) is an organisation in which hydrological institutes from the six main riparian states of the Rhine cooperate in the field of hydrological research. The member states of the CHR are: Switzerland, Austria, Germany, France, Luxemburg and The Netherlands. The main objective of the CHR is to study hydrological phenomena in the Rhine basin. The Commission' s first activities were mainly focused on making an inventory of hydrological data, which resulted in the publication of an extensive monograph on the Rhine basin. After that, the Commission began work on a new research programme to improve the water resources management in the Rhine basin. This programme included topics such as: standardization of data, improvement of hydrological forecasts and the description of extreme hydrological events. Nowadays, the Commission concentrates on a number of topical themes, such as: influence of climatic changes on the discharge of the Rhine, anthropogenic influences on the discharge regime, development of an alarm model for pollution transport, sediment transport in the Rhine basin and ecological rehabilitation of floodplains.