Process Integration is a common name for system oriented methods and integrated approaches to complex industrial process plant design. It is a multi disciplinary approach which consists of mathematical, thermodynamic and economic models and methods. Process Integration is a product of the increasing awareness of energy conservation needs in the industry. Some of the methods are therefore essentially related to examination of energy systems. Research in Process Integration has also been broadened to include raw material efficiency, emissions reduction and process operations. In the steel industry Process Integration projects can be further developed to powerful instruments for strategic management which includes decision making in connection with design of new plants, reshape of existing plants, or process development projects. Process constraints and alternative design options can be evaluated on equal terms. The implementation of recommended measures in this type of studies is often closely linked to other strategic decisions. This presentation gives an overview of past projects in Sweden where Process Integration has been applied in steel industry to minimise energy consumption, emissions and residue material flows. Some thoughts about the future use of Process Integration methods in the steel industry are also included.