The impact of human activities on the Himalayan biogeophysical, socioeconomic and cultural environments has been analyzed. The main man-induced activities which threaten the Himalayan Mountain ecosystems are unplanned land use, cultivation on steep slopes, overgrazing, major engineering activities, overexploitation of village or community forests, shifting cultivation, unplanned tourism and urbanization. Cold desert conditions prevail in 41 692 km2 of the northwestern Himalayas. The geomorphological conditions and arrested succession, checking the climax formation, are major causes of landslides. Sedimentation, changes in surface and groundwater hydrology and clearfelling of broad-leaved plant species have caused eutrophication, drying up of natural springs and receding of glaciers. Wild fauna like Musk deer (Moschus mischiferus) and Snow leopard (Panthera uncia) are now under threat due to changes in their habitats. Population pressure, migration and settlements are major causes of poverty and agglomeration, that jeopardize the Himalayan environment. Based on detailed environmental impact assessment, an ecosystem approach has been proposed for resources conservation and environmentally sustainable development of the Himalayas.