In the 1990s, significant progress was made in process synthesis concerning environmental issues, however the routine design procedures stay almost the same as before. This paper attempts to summarize the developments of this area in the last 10 years in order to remind chemical engineers of what has been accomplished to date and what should be possible in the near future from an industrial viewpoint. After discussing some original concepts and hierarchies, two aspects of conceptual design, synthesis of reaction paths and process flowsheet, are highlighted for environmental impact minimization. Finally, several points are identified for future research.