The purpose of this publication was to present the most important issues among scientific problems of the XIX International Grassland Sciences Congress in Brazil. The scientific problems presented and discussed in the course of the XIX International Grassland Sciences Congress in Brazil confirm the interdisciplinary nature of grassland sciences. It became evident from the discussions during the Congress that the wide range of issues dealt with in its course pointed to the need for closer co-operation between the International Grassland Congress and the International Rangeland Congress with the aim to better co-ordinate objectives and problems of meetings of scientists and researchers from different parts of the world. Typical grassland science investigations should be supported by studies from the area of basic sciences, for instance, plant physiology and biochemistry in order to reach a comprehensive elucidation of the observed processes and phenomena. The overall objectives of investigations on grassland ecosystems in the XXIst century will focus on seeking the mare efficient technologies of fibre and food production and defining the contribution and impact of grassland management on sustainable forming systems.