The article analyzes the history of creation of the UN Environment Program (UNEP), its legal status, organizational structure, functions of its governing organs, and basic directions of its activity. It concludes that the UNEP regional seas program carried out since 1974, covering now more than 140 states and 18 regions should be considered as the most dimensioned and significant project. It considers, in chronological sequence, international legal acts and strategies applied within the frameworks of this project in relation to the largest regions, entering into the UNEP regional seas program. It is underlined that a regional approach allows UNEP to concentrate its attention on specific issues of high priority for states of a separate region and in that way to help these countries to mobilize more fully their resources to combat marine pollution and ensure a sustainable management of coastal ecosystems. Besides, in the long term, such an approach should create basis for consideration of environmental problems of the World Ocean as a whole, on the global scale.