Section 102(2) (c) of the National Environmental Policy Act of 1969 of the United States requires an environmental assessment of the major federal actions that could significantly a-ffect environmental quality. The review is known as the NEPA assessment process, and the resulting document is called an Environmental Impact Assessment (EIS). Article 5 of the En-vironmental Preservation Law of ROK also introduced this system to a cereain extent. The purpose of this paper is, therefore, to review the general impacts of environmental pollution caused by newly proposed actions on air quality, water resources, and land use as well as specific impacts from the disposal of radiation wastes, operation of petroleum and ru-bber industries, construction of highways and dams, location of power plants and industrial co-mplexes, etc., in order to fully understand the importance of this system. Differences between American and Korean system are also briefly studied and reached to a conclusion that this important system should be understood in such a way as to link and uti-lize all conceivable disciplines and human knowledge in order to protect our environment by all means for ourselves and our coming generations as well.