Sanjaajamtsyn Altantuyaa (Mongolian: Санжаажамцын Алтантуяа; born March 6, 1976) is a Mongolian former swimmer, who specialized in sprint freestyle events. Altantuyaa competed for Mongolia in the women's 100 m freestyle at the 2000 Summer Olympics in Sydney. She received a ticket from FINA, under a Universality program, in an entry time of 1:04.00. She challenged seven other swimmers in heat one, including 15-year-olds Maria Awori of Kenya Nathalie Lee Baw of Mauritius. Diving in with the slowest reaction of 1.13 seconds, Altantuyaa fought her way from behind the pack to save a seventh spot over Tajikistan's Katerina Izmaylova by almost nine seconds in 1:10.22. Altantuyaa failed to advance into the semifinals, as she placed fifty-third overall in the prelims.