Along with J. O. M. Roberts of the United Kingdom, Dyhrenfurth co-led the unsuccessful 1971 International Expedition, which attempted to climb Mount Everest by two routes. The climbers included Dougal Haston and Don Whillans of the United Kingdom, Wolfgang Axt of Austria, Odd Eliassen of Norway, David Isles of the United States, Michel Vaucher of Switzerland, Carlo Mauri of Italy, Harsh Vardhan Bahuguna of India and Australian journalist Murray Sayle. The expedition ended in disarray after Bahuguna was killed high on the mountain.