The silvi-pastoral systems have been in practice for centuries in hot arid and semi-arid regions of India, new technical and socio-economic approaches are needed to increase productivity and sustainability. The complexity of process that determines the responses of grasses and trees to the environment and to each other requires large scale scientific assessment involving both "on station" and "on farm" researches. However, beneficial an alternative model of land utilisation may be. It will only be adopted if it is culturally and financially sound. But on the basis of available evidences from the researches carried out so far, it could be concluded that if compatible tree species are properly incorporated on pastures or on farm lands, over all biomass level could be enhanced, even under unfavourable climatic, edaphic and economic conditions in arid and semi-and regions.