Prosperi, a keen endurance runner, took part in the 1994 Marathon des Sables (Marathon of the Sands) in Morocco. Part way through the six-day 233 kilometre event a sandstorm caused Mauro Prosperi to lose his way. He ended up disoriented and ran in the wrong direction, ultimately running several hundred kilometres into Algeria. After 24 hours he ran out of food and water. He arrived at an abandoned Muslim shrine, with the corpse of a holy man in it, and survived by drinking his own urine. He found bats on the low ceilings which he decapitated and then ate the guts and drank the blood from, and he waited for rescue. A helicopter and a plane passed, but they failed to see him.
Not wishing to die a long drawn out death, Prosperi attempted to commit suicide in the shrine by slitting his wrists with a pen knife he had with him. The attempt failed - lack of water had caused Prosperi's blood to thicken and ultimately clotted the wound. He then regained his composure, and followed a Tuareg's advice prior to the start of the race to set his compass in the direction of early morning clouds and walk towards them. He walked in the desert and ate reptiles, insects, and cacti from dried wadis, before stumbling on an oasis, with a footprint next to it, and then some goats, and then a little girl who ran away towards a tent with women in it who gave him goat's milk and laid him in the shade outside. After nine days alone in the desert, he was found and taken to an Algerian military camp and from there to a hospital. He was 186 miles (299 km) off route, and had lost 18 kilograms (40 lb) in body weight. He received a hero's welcome back home in Italy, and media clamour.
His story of survival was later covered in a National Geographic Channel documentary entitled Expeditions To The Edge: Sahara Nightmare, as well as in an episode of the 2019 Netflix series Losers. It was also depicted in a Discovery Channel TV show hosted by the famous survival expert Bear Grylls, Bear Grylls: Escape from Hell.
Prosperi later entered the race again in 1998, but was halted by a severely stubbed toe.
Prosperi then re-entered the race yet again in 2012, completing the race in 34 and a half hours, in 131st place.
- How I drank urine and bat blood to survive BBC, retrieved on 27 November 2014
-  BBC Interview
- Run 151 miles in the desert? No sweat The Times, 13 April 2008, retrieved on 5 December 2010
- Running on empty MSN travel, retrieved on 5 December 2010
- Bear Grylls: Escape from Hell Discovery Channel, retrieved on 16 November 2014
- Marathon Des Sables Archived 2012-03-05 at the Wayback Machine SI Adventures, SI.com, retrieved on 5 December 2010