Results of a 1991 field investigation of the nature and extent of historical and contemporary human disturbance in the upper Barun valley, Makalu-Barun National Park and Conservation Area, Nepal, are presented. Forest structure, soils, pollen analysis, 14 C dating of buried wood samples, historical documents, and contemporary land-use trends of herders and mountaineering/trekking groups were assessed. Historical religious texts suggest that pilgrims may have been visiting sacred sites in the valley since the 14th century. Genealogical records indicate that regular seasonal grazing may have commenced in the 17th century with the easterly migration of the Sherpa people from the Solukhumbu region. Results of pollen analysis and 14 C dating suggest that historical anthropogenic disturbances in a dynamic environment, including the possibility of regular burning in a presumed attempt to increase pasture area, could have played significant roles in modifying the upper Barun valley landscapes. A corridor of disturbance related to contemporary indigenous and tourist use (tree harvesting, burning, grazing) was observed along the main valley trail, and impacts appeared to be growing in frequency and magnitude. Increased monitoring of these impacts is recommended, and priority research areas are identified. Support for, and monitoring of, existing park management policies which seek to recognize the rights of traditional users are also suggested as providing the most promising mechanisms for the sustainable conservation of the upper Barun valley's unique physical, cultural, and spiritual attributes.