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This study focused on estimating a methane (CH[sub 4]) inventory and developing mitigation options in South Korea, and was performed jointly in an integrated national research program on CH[sub 4] from rice fields conducted by three National Agricultural Research Institutes under the Rural Development Administration during 1993-1997. Methane emissions were measured by a closed chamber method, in rice plots at three locations (Suwon, Iksan, and Milyang) with the single rice cropping system. All experimental data from 5 years of study were summarized and used for calculating nation-wide CH[sub 4] emissions. Temperature, soil type, cultural practices, water management, organic matter management, and cultivar selection significantly affected the fluctuations of CH[sub 4] emissions. The two most promising mitigation options for reducing emissions were altered water management, in particular mid-season aeration by short-term drainage, and improved organic matter management, by promotion of aerobic degradation through composing or soil incorporation. Annual total CH[sub 4] emission in Korea changed from 410 Gg in 1990 to 339 Gg in 2000, due mainly to a decrease in the cultivated area of paddy rice. If we convert annual CH[sub 4] emission to Global Warming Potential as CO[sub 2] equivalent, it amounts to 7.1 M CO[sub 2] t yr[sup -1] of greenhouse gas emitted to the atmosphere in 2000 from the rice fields in Korea, which is just 5.3% of the annual CO[sub 2] emission from the industry and energy sector. More importantly, the balance between CO[sub 2] uptake by photosynthesis and CO[sub 2] emission is positive (a net sink), so that rice culture actually has net benefits for the global atmospheric carbon issue. Further reductions in emission amounts, by following recommendations in this article, could make these benefits even greater. [ABSTRACT FROM AUTHOR]