The pressures and impacts on the World’s Large Rivers have increased greatly in recent years, as a consequence of their exploitation to meet various human needs. Large rivers are particularly exposed to problems of multiple uses, often with conflicting aims. At the global scale, river systems are altered by increased nutrient loads leading to eutrophication of river stretches, navigation and hydropower plants deteriorating ecosystem functions and further human uses leading to far reaching problems further downstream. These challenges point also to the need for more integrated management approaches and consideration of catchment and river interactions emphasizing land use management and effects of these uses. At the global scale, there is currently no overview assessment of the current status of the world’s large rivers, the conflicting demands on such rivers, and likely future anthropogenic impacts, as well as the potential for restoration, improvements in integrated management and the associated problems caused by their multiple uses. The International Conference on ‘The Status and Future of the World’s Large Rivers’ and this Special Issue in Hydrobiologia on ‘Impact of human activities on biodiversity of large rivers’ aim to provide a global forum for a wide-ranging discussion of key issues related to research on large rivers and to their effective and sustainable management, involving both scientists and decision makers. The sequence of papers in the special issue highlights the current situation in different river systems with regard to river conservation and rehabilitation, and human impacts on flora and fauna. Beside seven other Special Issues in SCI journals, this Special Issue is an outcome of the 1st International Conference on the Status and Future of the World’s Large Rivers held in April 2011 in Vienna (http:// worldslargerivers.boku.ac.at/wlr/). The 2nd conference will take place in Manaus, Brazil, in July 2014.