Rice-wheat cropping system (RWCS) is the most widespread cropping system in the Indo-Gangetic Plains IGP) covering more than 13 m ha in S.Asia. The RWCS is fundamental to income, nutrition requirements, employment and livelihoods of of people in IGP. The availability of high yielding, photoperiod non-sensitive and medium duration varieties of both rice and wheat during the late sixties and seventies made not only the rice-wheat rotation possible but also brought vast areas under the system, leading to transformation of agriculture in the IGP. The production and productivity of crops increased by several fold during the Green Revolution period (1965-85), especially in the irrigated, high-input intensive rice-wheat system areas , while the same was not true in the rainfed areas in the eastern parts of IGP. However, these growth rates could not be sustained during the post Green Revolution period i.e., after 1985. A decline in the profitability of the RWCS was also reported. The annual growth rate of total factor productivity (TFP) was reported to decline from 2.9% during the Green Revolution period to -0.4% thereafter. In view of the reported adverse changes in climate and natural resource base and also the declining TFP growth rates, achieving the required growth rates of 2.5% per annum in the production of food grains in the coming years appears to be a daunting task. There is evidently a growing concern about the sustainability of the RWCS and consequently about the sustenance of the livelihoods and nutrition security of millions of rural and urban poor in the region. This paper attempts to review the status of the RWCS during the Green Revolution period and identify the issues causing concern about its sustainability during the post Green Revolution period. Some strategies that could possibly reverse the trends and lead to system sustainability are also presented.