The Karakoram Highway has been constructed through extremely difficult high arid mountainous terrain characterized by long, steep slopes, highly fractured and heavily weathered rocks, extensive areas of debris accumulation and locally high rates of geomorphological activity. The problems for road construction imposed by difficulties of access and remoteness have been compounded by rockslope instability, debris flows, river and meltwater surges, and fluctuating glacier snouts. As a consequence, the employment of sophisticated engineering techniques was abandoned in favour of widespread blasting and an extended period of labour-intensive maintenance. This paper is concerned with an 147 km stretch of the Highway and essentially subdivides into two parts. The first part describes the terrain conditions and main hazards posed to road construction, and includes a geomorphological assessment of the chosen alignment. The second section presents the results of a detailed survey of 128.8 km of the Highway in terms of the patterns of disruption experienced during the first three years of its life, and the distribution of a variety of hazards which will continue to endanger the road. This survey clearly reveals the importance of a good appreciation of geomorphological processes to highway engineering in arid mountains, as well as indicating the potential for geomorphological inputs to highway design.